COLON AND RECTUM 1 · 2021. 5. 14. · COLON AND RECTUM 1 FRIDAY, MAY 21, 2021 Colon and Rectum 1 Poster ID: 3526203 EFFICACY AND SAFETY OF COLD SNARE POLYPECTOMY (CSP) OF INTERMEDIATE

COLON AND RECTUM 1

FRIDAY, MAY 21, 2021Colon and Rectum 1Poster

ID: 3526203EFFICACY AND SAFETY OF COLD SNARE POLYPECTOMY(CSP) OF INTERMEDIATE SIZED COLORECTAL POLYPS10 - 15 MM- A PROSPECTIVE OBSERVATIONALFEASIBILITY TRIAL (COLDSNAP-1)Paul Rechberger*, Jörg D. Ulrich, Mohamed Abdelhafez,Guido von Figura, Jeannine Bachmann, Johannes R. Wiessner,Alexander Herner, Tobias Lahmer, Veit Phillip, Ulrich Mayr,Bernhard Haller, Moritz Jesinghaus, Roland Schmid, Christoph SchlagIntroduction: Cold Snare Polypectomy (CSP) has been gaining interest in recentyears and is already an integral part of guidelines for polyps <10mm in size. Incontrast to hot snare polypectomy (HSP), CSP doesn’t involve electrocautery andless adverse events (AE) with comparable resection rates have been shown. How-ever, little is known about the feasibility of CSP for colorectal polyps of 10 to 15 mm.Therefore, this study evaluates the efficacy and safety of CSP for these polyps. Goalsand Methods: This ongoing prospective observational study investigates the feasi-bility and safety of CSP for adenomatous polyps and sessile serrated lesions (SSL)10-15 mm. Suitable polyps are removed by CSP using a hybrid snare. In case offailure conversion to HSP with the same snare is allowed. The primary outcome isthe histological complete resection rate, determined by pathologically negativemargins of the specimen and no residues adenomatous material obtained from fourbiopsies of the resection site. Secondary outcomes are en-bloc resection rate, failureof CSP with conversion to HSP and immediate bleeding. Furthermore, the incidenceof adverse events such as delayed bleeding and perforation are observed. Results: Bynow a total of 24 patients with 40 polyps were included. The mean polyp size was12.1 mm, 75% (30/40) of these polyps were adenomas and 25% (10/40) were SSL.The histological complete resection rate by CSP was 83.3% (25/30). En-bloc resec-tion could be achieved in 60% (18/30). Primary CSP failed with 10 (25%) polyps mostlikely due to large amount of tissue within the snare. These polyps were succesfullyremoved after conversion to HSP with the same snare. Immediate bleeding occurredwith 16 (53.3%) lesions, which were treated by hemoclips (2.13 Clips on average).No other adverse events were observed. Conclusion: CSP seems to be efficient andsafe in removing 10 – 15 mm colorectal polyps. A hybrid snare seems to be particularadvantageous for larger polyps as it allows immediate conversion to HSP if CSPmight fail.


ID: 3523472LONG-TERM OUTCOMES OF WESTERN-BASEDENDOSCOPIC SUBMUCOSAL DISSECTION FORCOLORECTAL LESIONSMaselli Roberta, Marco Spadaccini*, Paul J. Belletrutti,Piera Alessia Galtieri, Simona Attardo, Silvia Carrara, Alessandro Fugazza,Elisa Chiara Ferrara, Gaia Pellegatta, Andrea A. Anderloni, andrea iannone,Cesare Hassan, Alessandro RepiciBackground & aims: In Asian countries, the safety and efficacy of endoscopicsubmucosal dissection(ESD) is well-established for the minimally invasive treatmentof colorectal (CR) neoplasia. Favorable long-term outcomes have been reported interm of adenoma recurrence. The role of ESD for CR lesions in Westerncommunities is unclear and its adoption is still limited. This may be attributed to thedisappointing technical outcomes in preliminary studies, along with the lack of long-term data coming from Western centers. The aim of this study is to assess the long-term outcomes of a large cohort of patients treated with colorectal ESD in a tertiaryWestern center. Methods: Between February 2011 and November 2019, a retro-spective analysis of a prospectively maintained database was conducted on patientstreated by ESD for colorectal lesions at Humanitas Research Hospital in Milan, Italy.The primary outcome considered for this study was the recurrence rate. Secondaryoutcomes were en-bloc, and R0 resection rates, procedural time, adverse events, andneed for surgery. The curative resection rate was assessed for submucosal invasivelesions. Statistical analysis included descriptive statistics, Chi square and

Kaplan-Meier tests. Results: Over the study period, 327 consecutive patients (medianage: 69 (IQR: 60-76) years old; 201 - 61.5%- males) were included in the analysis. The90.8% of lesions were resected in an en-bloc fashion. The rate of R0 resection was83.1% (217/261) and 44.0% (29/66) for standard and hybrid techniques, respectively.Submucosal invasion and piece-meal resection independently predicted R0 resec-tions. A total of 18 (5.5%) intra-procedural AEs (11 perforations and 7 bleedings) and12 (3.7%) post-procedural AEs (2 perforations and 10 bleedings) occurred. The twopatients readmitted for a post procedural perforation were referred for surgery andwere excluded from the follow-up analysis. Seventy-five out of 327 lesions (23.0%)resulted in CR neoplasia with submucosal invasion. Fifty-seven of them showedhigh-risk features of nodal involvement (non-curative resection) and were excludedfrom the follow-up analysis, which finally involved 268 patients. Eighteen adenomarecurrences per 1,000 person- years (15 cases, 5.6%) were detected in a medianfollow-up time of 36 months. Any recurrence was detected after the 12 months FUendoscopy. No carcinoma recurrences were observed. R1 resection and intra-pro-cedural adverse events independently predicted recurrences. Conclusion: ColorectalESD, especially with standard approach, is a safe and effective option for managingcolorectal neoplasia in a Western setting, with short and long-terms outcomescomparable to published Eastern series. Achieving en-bloc, R0 resections, avoidingintra-procedural adverse events might minimize the risk of adenoma recurrence.


ID: 3521920CLINICOPATHOLOGICAL CHARACTERISTICS OFSERRATED POLYPOSIS SYNDROME: RESULTS OF AMULTICENTER STUDY BY THE COLORECTAL SERRATEDPOLYPOSIS SYNDROME (SPS) STUDY GROUP IN JAPANYasutsugu Shimohara*, Yuji Urabe, Shiro Oka, Takashi Hisabe,Atsushi Yamada, Hiro-O Matsushita, Hirotsugu Sakamoto, Joichiro Horii,Daisuke Watanabe, Hirotsugu Eda, Fumika Nakamura,Hironori Yamamoto, Tetsuji Takayama, Takayuki Matsumoto,Shinji Tanaka, Hideki IshikawaBackground and aim: Serrated polyposis syndrome (SPS) is one of the colorectalpolyposis, characterized by the occurrence of multiple serrated lesions.SPS isknown to have a higher risk of colorectal carcinoma (CRC). The aim of this study wasto clarify the clinicopathological characteristics of SPS in Japan. Materials andmethods: We investigated the clinicopathological characteristics in patients with SPSaccumulated through the "Multicenter Study on clinicopathological characteristics ofSPS (UMIN 000032138)" by the Colorectal Serrated Polyposis Syndrome (SPS) StudyGroup, which was donated by the Japanese Society of Gastroenterology (JSGE). Inthis study, we diagnosed patients with SPS according to 2019 World Health Orga-nization (WHO) SPS diagnostic criteria as follows; I) �5 serrated lesions/polypsproximal to the rectum, all being �5mm in size, with at least 2 being �10mm in size;and II) >20 serrated lesions/polyps of any size distributed throughout the largebowel, with �5 being proximal to the rectum. Results: A total of 94 patients werediagnosed with SPS at 9 institutes during a period from January 2001 until December2017. The median (range) number of resected lesions per apatient was 6 (0�85).The median age at the diagnosis of SPS was 65 years (22�85), 54 patients (57.4%)were male, and 17 patients (18.1%) had a history of CRC. Eighty-seven patients(92.6%) satisfied the WHO diagnostic criteria I and 16 (17.0%) criteria II. Nine pa-tients (9.6%) simultaneously satisfied criteria I and II. Among the overall 1689 polypsFound in the patients, 926 lesions were resected. The pathological findings of the926 resected lesions were as follows; 387sessile serrated lesions, 252 hyperplasticpolyps, 245 tubular adenomas, 13 traditional serrated adenomas, 18 Tis carcinomas,4 T1 carcinomas, and 7 advanced carcinomas. In twenty-eight of 32 patients withCRC, CRCs were detected at the index colonoscopy. Ten CRCs (7 Tis carcinomas, 2T1 carcinomas, and 1 advanced carcinoma) were found during surveillance colo-noscopy. Two patients underwent surgery, with one of whom died of primary cancer60 months after the surgery. Of the 32 patients with CRC, 27 patients (84%) satisfieddiagnostic criteria I, 2 patients (6.3%) diagnostic criteria II, and 3 patients (9.4%)diagnostic criteria I and II. The prevalence of CRC was higher in patients whosatisfied diagnostic criteria I than in those who satisfied diagnostic criteria II.Conclusion: Of the 94 SPS patients who satisfied WHO diagnostic criteria, 32 pa-tients (34%) had CRCs. Patients with SPS have a high risk of CRCs and should un-dergo surveillance colonoscopy.

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ID: 3522946EC-V (ENDOCYTOSCOPIC VASCULAR) CLASSIFICATIONIS USEFUL FOR NOT ONLY QUALITATIVE DIAGNOSISBUT ALSO PATHOLOGICAL DIAGNOSISShinei Kudo*, Miyuki Kaneshiro, Masashi Misawa, Kenichi Mochizuki,Hiroki Nakamura, Yuta Kouyama, Tomoyuki Ishigaki, Katsuro Ichimasa,Shingo Matsudaira, Naoya Toyoshima, Yuichi Mori, Noriyuki Ogata,Toyoki Kudo, Tomokazu Hisayuki, Takemasa Hayashi,Kunihiko Wakamura, Hideyuki Miyachi, Toshiyuki Baba, Fumio IshidaBackgrounds and Aims: Endocytoscopy (EC) is a kind of contact type endoscopethat allows in vivo, real-time cellular observation with 520-times magnification,launched since 2019. Thus far, narrow-band imaging (NBI) could make it possible toanalyze the surface microvessels of colorectal lesions for differentiating neoplasmsfrom non-neoplasms and for predicting the histopathological diagnosis. EC com-bined with NBI (EC-NBI) enables in vivo observation of blood vessels in more detailcompared to conventional magnification power. The aim of this study was to vali-date the evidence whether the observation of surface microvessels using EC-NBI wasuseful in predicting the histopathology of colorectal lesions. Methods: In this study,622 patients who underwent complete colonoscopy and endoscopic or surgicaltreatment between April 2006 and December 2019. A total of 997 lesions (118 Non-neoplastic polyps, 640 adenomas, 77 intramucosal cancer(M), 21 slightly invasivesubmucosal cancer (SMs) and 141 massively invasive submucosal cancer(SMm))were retrospectively evaluated. We used the Kudo classification for the degree ofsubmucosal invasion. SMs cancer without vessel permeation does not metastasize.In contrast, SMm lesions show a substantial proportion (w10%) of lymph nodemetastasis. We named the ultra-magnified microvessel findings as EC-V classificationand classified into the following 3 groups: EC-V1, the surface microvessels were veryfine or obscure; EC-V2, the surface microvessels were clearly seen and showed aregular vessel network, and their caliber and arrangement were uniform; and EC-V3,the microvessels were thick, and their caliber and arrangement were non-homoge-neous. Corresponding histopathology among these classifications were as follows;EC-V1 corresponds to hyperplastic, EC-V2 corresponds to adenoma and EC-V3corresponds to SMm. Result: The sensitivity, specificity and accuracy of EC-V1 fordiagnosis of hyperplastic polyp were 87.2%, 98.6% and 97.3%, respectively. Secondlythe sensitivity, specificity and accuracy of EC-V2 for diagnosis of adenoma or M orSMs were 97.2%, 84.6% and 93.9%, respectively. Similarly the sensitivity, specificityand accuracy of EC-V3 for diagnosis of SMm were 82.3%, 98.9% and 96.6%,respectively. Conclusion: EC-V classification was useful for predicting the histopa-thology of colorectal lesions.


ID: 3523799REFERRAL PATTERNS, POLYP FEATURES, AND CLINICALOUTCOMES FOR COLORECTAL POLYPS ≥ 2 CM IN ALARGE TERTIARY CARE HEALTH SYSTEMBao Sean Nguyen*, Camille Soroudi, Allen R. Yu, Brandon Smith,Madeline Treasure, Sartajdeep Kahlon, Stephen Kim, Adarsh M. Thaker,Liu Yang, Folasade (Fola) P. MayIntroduction: Although 2020 US Multi-Society Task Force guidelines recommendendoscopic removal of colorectal polyps �2cm by an experienced gastroenterolo-gist, considerable heterogeneity exists in the management of these patients. Weexamined referral patterns, polyp features, and clinical outcomes for patients withcolorectal polyps �2cm at a tertiary care health system. Methods: We used aninternally developed natural language processing algorithm to identify all patientsdiagnosed with at least one colorectal polyp �2cm on index colonoscopy between 1/1/2013 and 12/31/2017 across 5 endoscopy units within a large health system. Weexcluded patients with a history of colorectal cancer (CRC), inflammatory boweldisease, or familial polyposis syndromes. We performed manual chart review toconfirm large polyp status and collect patient data on demographic and clinicalfactors, referrals, procedural management, and clinical and histologic outcomes. Theprimary outcome was the proportion of patients referred to therapeutic endoscopy(TE), surgery, TE plus surgery, other, or who received care only with generalgastroenterology (GI). Secondary outcomes included polyp features and 3-yearclinical outcomes (high-risk neoplasia (HRN), adenocarcinoma, and death) associ-ated with each type of referral. We used chi-square and Fisher’s exact tests toexamine associations between referral pattern, polyp features, and clinical out-comes. Results: The study cohort included 212 patients who underwent index co-lonoscopy with general GI (Table 1). In index colonoscopies, endoscopic resection

was attempted or achieved in 90 (42.5%) cases; 58 (27.4%) were resected en blocand 29 (13.7%) in piecemeal fashion. Endoscopic mucosal resection was used in 29(23.8%) cases. Average polyp size was 2.7cm (s.d. 1.04). Referral patterns were: 102(48.1%) to TE, 17 (8.1%) to surgery, and 2 (0.9%) to TE plus surgery or other; 90(42.5%) were not referred and continued follow-up with general GI. Polyp featuressignificantly associated with referral to TE were large size, ileocecal valve location,and flat morphology (all p<0.01). Concern for malignancy was associated withreferral to surgery (p<0.01). At the end of the 3-year follow-up period, there were nostatistically significant differences in incidence of HRN, adenocarcinoma, or death byreferral type (Table 2). Conclusions: More patients with colorectal polyps �2cmwere referred to therapeutic endoscopy than surgery without significant differencesin 3-year clinical outcomes. Polyps with large size, ileocecal valve location, and flatmorphology were more likely referred to therapeutic endoscopy while polyps withconcern for malignancy were more likely referred to surgery. Future studies shouldevaluate longitudinal clinical outcomes by referral pattern and procedural manage-ment for larger cohorts of patients with colorectal polyps �2cm.

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ID: 3520297UNDERWATER COLD SNARING LARGE (≥10MM) NON-PEDUNCULATED, NON-BULKY COLORECTAL LESIONSIS FEASIBLE WITH HIGH EN BLOC RESECTION RATESAndrew W. Yen*, Joseph W. Leung, Felix W. LeungBackground: Adverse events are rare with cold snare resection, but cold techniquesare mainly reported for �9mm lesions out of concern for incomplete resection orinability to remove larger lesions en bloc [Dig Endosc 2017;29:594]. In a non-dis-tended, water-filled lumen (gas excluded), colorectal lesions are not stretched andare more compact. Complete capture by snare and en bloc resection underwaterwith electrocautery, even of large lesions appears to be possible [GIE 2015;81:713].Achieving an adequate depth of resection with underwater snaring compared topolypectomy in a gas distended colon has also been observed and is another po-tential advantage [Dig Endosc 2019;31:662]. Aims: We assessed the feasibility ofunderwater cold snare (UCS) resection of �10mm non-pedunculated, non-bulky(�5mm elevation) colorectal lesions in a VA endoscopy unit. Methods: Analysis wasperformed on an observational cohort with lesions removed by UCS without sub-mucosal injection (SI) during routine outpatient colonoscopy from 1/2016 to 11/2020. Pedunculated and/or bulky lesions where mechanical transection of tissue bycold techniques can be limited, and patients enrolled in other clinical trials, were notincluded. A single endoscopist performed procedures using a thin wire cold orhybrid snare. Attempts were made to completely remove lesions en bloc. Results:Fifty-three lesions (mean 15.8mm [SD 6.9]; range 10-35mm) were removed by UCSfrom 44 patients. Image 1 shows patient demographics and lesion characteristics.Image 2 compares UCS to a cohort of �10mm non-pedunculated lesions removedby underwater hot snare without SI and conventional submucosal injection, lift andhot snare (EMR) techniques from the author’s previously published RCT [GIE 202091:643] and reports from the literature. Significantly more lesions were successfullyresected en bloc by UCS (84.9% [45/53]; pZ0.03) compared to conventional EMR(60.4% [32/50]) with no significant immediate adverse events. Results were drivenby high en bloc resection rates for 10-19mm lesions (97.3% [36/37]; pZ0.01).Omission of SI and forgoing prophylactic clipping of post resection sites conservedexpenses and did not result in increased short-term adverse outcomes. Limitations:Retrospective study; single unblinded endoscopist; VA patients. Conclusion: UCS of�10mm non-peduncuated, non-bulky colorectal lesions is feasible with high en blocresection rates. No clinically significant short-term adverse outcomes were observed.Decreased resource utilization with avoidance of prophylactic clipping and SI, whichrequires an injection needle and injectate solution, as well as fewer piecemeal re-sections that require closer follow up, are also potential benefits. A RCT comparing

UCS vs. hot snare techniques for �10mm non-peduncuated, non-bulky colorectallesions to assess efficacy, adverse outcomes and costs is indicated.


ID: 3526923ENDOSCOPIC MUCOSAL RESECTION (EMR) VS.ENDOSCOPIC SUBMUCOSAL DISSECTION (ESD) FORLARGE RECTAL POLYPSFnu Chesta*, Anmol Singh, Meher Oberoi, Prabh G. Singh,Ganeev Bhangoo, Kevin T. Behm, Louis M. Wong Kee Song,Navtej S. ButtarBackground and Aims: Endoscopic mucosal resection (EMR) allows for fasterresection and shorter procedure duration while endoscopic submucosal dissection(ESD) facilitates en bloc resection of large/complex polyps for more accuratehistopathological evaluation. Our aim was to compare the efficacy and safety of EMRand ESD for rectal polyps �20 mm. Methods: Patients referred for large (>20 mm)rectal polyp resection between 01/2011 and 12/2019 were identified from ourendoscopy database using Advanced Cohort Explorer. All EMR and ESD were per-formed by two experienced endoscopists. Data were abstracted for patient demo-graphics, polyp characteristics, procedural details, adverse events, and polypresidual/recurrence. Results: Out of 525 patients with large (nZ762) colorectalpolyps, 92 patients (97 rectal polyps) met inclusion criteria, of which 54 polyps were


Abstracts


resected by EMR (49 patients) and 43 by ESD (43 patients). Mean polyp size was 32mm (range 20�70 mm) and 38 mm (range 30�84 mm) for EMR and ESD, respec-tively (pZNS). Fewer polyps were at the dentate line in the EMR group compared tothe ESD group (7.4 vs 41.8%, p<0.05). Endoscopic clips were used more frequentlyin the EMR group compared to the ESD group (p<0.05). Four (8.1%) patients in theEMR group underwent surgery for adenocarcinoma in the resected specimens andpost-surgical specimens revealed no residual adenocarcinoma in two. Additionally,two patients in the EMR group elected surgery for incomplete resection. Three(6.9%) patients in ESD group underwent surgery for invasive adenocarcinoma, withresidual malignancy found in one. One additional patient required surgery in theESD group due to perforation. Procedure related delayed bleeding was encounteredin one (2%) patient in the EMR group (managed by clip placement) and one (2.3%)patient in the ESD group (managed by hemostatic forceps). The rate of delayedadverse events rates trended higher for ESD relative to EMR (20.9% vs. 10.2%,pZNS). Transmural burn syndrome was observed in more patients post ESD thanpost EMR (9.3% vs 0%, pZ0.04). In the ESD group, three patients had delayedbleeding and one had perforation requiring endoscopic suturing. In the EMR group,three patients had delayed bleeding and two had microperforations managedconservatively. Two (4.7%) patients in the ESD group and three (6.1%) in EMRgroup had residual/recurrent lesions that were all managed endoscopically.Conclusion: Both EMR and ESD are safe and effective for the resection of large rectalpolyps. However, ESD patients were more likely to have complex polyps abuttingthe dentate line. To overcome selection bias, a randomized trial of EMR vs ESD forrectal polyps is warranted.

Outcomes of EMR vs ESD for large rectal polyps


ID: 3526513RISK FACTORS FOR STENOSIS AFTER ENDOSCOPICSUBMUCOSAL DISSECTION OF LARGE LESIONS OF THERECTUMDaniel T. Rezende*, Fabio S. Kawaguti, Bruno Martins,Adriana V. Safatle-Ribeiro, Caio Sergio R. Nahas, Carlos F. Marques,Amanda A. Pombo, alisson L. Santos, Oddone F. Braghiroli,Ulysses Ribeiro, Sergio C. Nahas, Fauze Maluf-FilhoBackground: The development of stenosis in the rectum after endoscopic submuco-sal dissection (ESD) is one of the most frequently delayed complication, rangingfrom 4.2 to 19.7 % of the resections of large rectal lesions. Circumferential mucosaldefect greater than 90% seems to be only independent predictor of stenosis.Morphology and size have not shown relation with the occurrence of strictures.However, due to the small number of cases reported, the factors that really pre-dispose to stenosis after ESD of rectal lesions may be not yet fully understood. Aim:

The aim of this study was to identify the main risk factors for stenosis and symptomsafter ESD of large rectum lesions and their treatment. Materials and Methods: Weretrospectively analyzed all patients identified from a prospectively maintaineddatabase of patients submitted to ESD for rectal lesions between July 2010 andJanuary 2020. Patients were followed in regular appointments and in scheduledsurveillance exams. Primary outcomes were post-ESD stenosis – total or partial. Totalstenosis was defined when the rectal lumen became too narrow to allow passage of astandard 12.8 mm diameter endoscope. Partial post-ESD stenosis was defined whenthe rectal lumen became narrow enough to difficult the passage of a standardendoscope, but not too narrow to impossibilities the passage. Secondary outcomeswere the presence of symptoms related to stenosis and the respective treatmentwhen necessary. Statistical analyses were performed using SPSS software. Results: Atotal of 98 resections were performed in the period (median size 68 mm). Thirteenwere excluded from analysis: 8 due to complications or deep invasion, 4 were notcurative and 1 discontinued follow up. In a total of 85 patients analyzed, 69 did notpresent stenosis, 9 presented total stenosis and the other 7 partial stenosis (mediansize 108 mm, p<0.05). The size of the lesion and the degree of circumferentialmucosal defect were significative different between the two groups. However, onlythe grade of mucosal defect greater than 90% persisted as a risk factor for stenosisafter multivariated analyses (table 1).7 patients with stenosis presented severesymptoms and were treated with consecutive dilation sessions (table 2). Total ste-nosis and the distance from anal verge shorter than 5 cm showed significative dif-ference between the patients with or without symptoms (table 1). Conclusions: Alarge lesion with mucosal defect greater than 90% is the main isolated risk factor forstenosis after submucosal dissection of large rectum lesions. Total stenosis afterprocedure and distance to anal board shorter than 5 cm are more likely to presentsymptoms. Those patients require special attention and earlier return.

Table 1. Comparsion between with and without stenosis groups and be-tween with and without symptoms groups

Table 2. Characteristics of patients and treatments for stenosis


ID: 3524934MALIGNANT LARGE BOWEL OBSTRUCTION ANDCOLONIC STENTING AS SAFE BRIDGE TO SURGERY - ACLINICAL AUDIT OF EFFICACY AND SAFETY IN ATERTIARY CENTREGarrett Kang*, James Weiquan Li, Andrew Kwek, Eng Kiong Teo,Kwong Ming Fock, Tiing Leong AngIntroduction: Approximately 8-15% of colorectal cancers (CRC) present with acutemalignant large bowel obstruction (MBO). Emergency surgery in this setting isassociated with high post-operative mortality and morbidity. Self-expandable metalstent (SEMS) in MBO has been used as bridge-to-surgery (BTS) and as destinationtherapy for palliation in unresectable tumours. We aimed to conduct a clinical auditto review the safety and efficacy of SEMS placement in patients with MBO in our


Abstracts


institution. Methods: Review of data was conducted on a prospectively maintainedelectronic patient database in a tertiary referral centre in Singapore. All consecutivepatients undergoing SEMS insertion for MBO were included in the audit. Technicalsuccess was defined as successful deployment of the SEMS across the malignantstricture without complications. Clinical success was defined as colonic decom-pression within 24h without requiring further surgical intervention. Rates of com-plications were studied. Median time to surgery, types of surgery and rates ofrecurrence of our cohort were recorded. Results: 92 patients underwent emergentSEMS placement for MBO from September 2013 to November 2020. Mean age of ourpatients was 67.6 years (� 14.0 years), 48/92 (52%) were male. Obstruction waspredominantly distal to splenic flexure: rectum (4/92, 4.3%), rectosigmoid (19/92,20.7%), sigmoid (34/92, 37.0%), descending (26/92, 28.3%) and transverse colon (9/92, 9.8%). Mean length of CRC was 4.2cm (� 2.1cm). Technical success was 94.6%(87/92) and clinical success was 94.3% (82 out of 87). Perforation occurred in 4/92(4.3%) patients. Stent migration occurred in 4/92 ( 4.3%) of patients. Tumourovergrowth occurred in 3/92 (3.3%%) of patients. There were no cases of bleeding.60/92 (65.2%) of SEMS were inserted as BTS. Median time to surgery was 20 days(range 2-57 days). 50/60 (83.3%) of patients underwent minimally invasive surgery(robotic-assisted 9/60, 15%; laparoscopic 41/60, 68.3%) while 10/60 (16.7%) under-went open surgery. Rate of primary anastomosis was 96.7% (58/60). 39 patients hadfollow-up for more than 1-year post-treatment (median 34 months). Local recur-rence and distant metastasis was observed in 4/39 (10.3%) and 5/39 (12.8%),respectively. Conclusion: SEMS insertion in acute MBO has high technical andclinical success rates. The main complications were perforation, stent migration andtumour overgrowth. Majority of patients in our audit underwent minimally invasivesurgery and primary anastomosis after successful BTS.


ID: 3520164LONG-TERM PROGNOSIS AFTER ENDOSCOPICSUBMUCOSAL DISSECTION FOR COLORECTAL TUMORSIN PATIENTS AGED OVER 80 YEARSTomoyuki Nishimura*, Shiro Oka, Yuki Kamigaichi, Hirosato Tamari,Yasutsugu Shimohara, Yuki Okamoto, Katsuaki Inagaki, Kenta Matsumoto,Hidenori Tanaka, Ken Yamashita, Yuki Ninomiya, Yasuhiko Kitadai,Shinji TanakaBackground: In Japan, endoscopic submucosal dissection (ESD) has been standard-ized for large colorectal tumors, however its validity in the elderly population isunclear. We aimed to evaluate the safety and efficacy of ESD for colorectal tumors inelderly patients aged over 80 years. Methods: Colorectal ESD was performed on 178tumors in 165 consecutive patients aged over 80 years between December 2008 andDecember 2018. The patients who could be prepared for colonoscopy with morethan 1-L bowel cleansing agent were indicated for ESD. We retrospectively evaluatedthe clinicopathological characteristics and clinical outcomes of colorectal ESD andassessed the prognosis of 160 patients followed up for more than 12 months.Results: The mean patient age was 83.7+3.1 years. The number of patients with co-morbidities was 100 (62.5%). The most common comorbidity was hypertension(52%), and the second one was cardiac disease (25%). Among all patients, 106(64.2%) were categorized as the American Society of Anesthesiologists classificationof physical status (ASA-PS) class 1 or 2, and 59 (35.8%) as class 3. The mean pro-cedure time was 97.7�79.3 minutes. The rate of histological en bloc resection was93.8% (167/178). Delayed bleeding in 11 cases (6.2%) and perforation in 7 cases(3.9%) were treated conservatively. The 5-year survival rate was 89.9% (mean follow-up time: 35.3+27.5 months). A total of 25 deaths during prognostic observationwere noted. Primary cancer death accounted for one patient who required absolutesurgery indication due to a positive vertical margin in ESD specimens. The patientrefused additional surgery, and recurrence occurred, comprising lung and livermetastasis, within 8 months after ESD. Overall survival rates were significantly lowerin the non-curative resection group that did not undergo additional surgery than inthe curative resection group (PZ0.0152) and non-curative group that underwentadditional surgery (PZ0.0259). Overall survival rates were higher for ASA-PS class 1or 2 patients than for class 3 patients (PZ0.0105). Metachronous tumors (>5 mm)developed in 9.4% of patients. Conclusions: ESD for colorectal tumors in patientsaged over 80 years is safe. Colorectal cancer-associated deaths were preventedregardless of ASA-PS although comorbidities pose a high risk of poor prognosis.


ID: 3524655REFERRAL PATTERNS FOR ENDOSCOPIC RESECTIONOF LARGE COLON POLYPS AMONG ACADEMIC VS.COMMUNITY-BASED GASTROENTEROLOGISTS: ASINGLE ACADEMIC TERTIARY CARE CENTEREXPERIENCEPhilip Kozan*, Allen Yu, M. P. Fejleh, Alireza Sedarat,V. Raman Muthusamy, Stephen KimIntroduction: Endoscopic mucosal resection (EMR) is a safe and cost-effectivemethod of removing large, benign colon polyps with a low risk of complicationsand high rates of clinical success. As rates of colon polyps being referred for EMRcontinue to rise, it is important to recognize and understand trends in referral pat-terns for colon polyp EMR. Methods: A retrospective chart review was performed toidentify patients who underwent an index colonoscopy with a colon polyp greaterthan or equal to 1 cm in size who were subsequently referred for colon polyp EMRwith an interventional endoscopist at a single tertiary academic center over oneacademic year (2018-2019). Our primary outcome was to determine if there was adifference in colon polyp size referred for EMR between general gastroenterologistsfrom within the academic center and community-based gastroenterologists. Statis-tical analysis was performed with Welch’s t-test and Chi-square test. Results: In thestudy cohort, 267 total patients were referred for endoscopic mucosal resection oflarge colon polyps that were unable to be removed at index colonoscopy. Of the 173(64.8%) patients referred by gastroenterologists from within the academic institu-tion, a total of 205 large colon polyps were identified and removed. Among the 94(35.2%) patients referred from community-based gastroenterology practices, a totalof 111 large colon polyps were identified and removed. There were no significantdifferences in the age, gender, and race of the patients in the two groups (Table 1).Gastroenterologists from community practices outside of the academic institutionreferred larger colon polyps than those who practiced within the academic healthsystem (27.3�15.2 cm v. 22.1�13.9 cm, p Z 0.003). In addition, academic gastro-enterologists were more likely to refer colon polyps that were �15 mm (nZ86 vs.nZ27, pZ0.001) as compared to community-based gastroenterologists (Table 2).Conclusion: Community-based gastroenterologists refer larger colon polyps than ac-ademic gastroenterologists for endoscopic mucosal resection. More specifically, thecommunity-based gastroenterologists are less likely to refer colon polyps � 15 mmin size. These findings warrant further investigation in emerging referral patterns forcolon polyp EMR.


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ID: 3521534MAJORITY OF INDIVIDUALS WHO HAVE DECLINEDCOLONOSCOPY AND STOOL TEST ARE WILLING TOUNDERGO BLOOD TEST FOR CRC SCREENINGYongyan Cui*, Anika Zaman, Anne M. Kaminsky, Gabriel Castillo,Craig T. Tenner, Scott E. Sherman, Jason A. Dominitz, Peter S. LiangIntroduction: One-third of Americans between age 50 and 75 years are not up todate with colorectal cancer (CRC) screening. Barriers to colonoscopy and stool-based testing have led to ongoing interest in blood-based screening tests. As part ofa clinical trial assessing the impact of offering a Septin9 blood test for CRC screeningin individuals who’ve previously declined colonoscopy and fecal immunochemicaltesting (FIT), we conducted a questionnaire to understand patient perspectives ondifferent CRC screening methods. Methods: Patients receiving care at a VA medicalcenter who were aged 50 to 75 years, at average risk for CRC, not up to date withscreening, and with documented refusal to screening in the prior 6 months weresent a questionnaire as part of the invitation to join the trial. Questionnaire itemsincluded demographics, health status, medical history, and perspectives on differentCRC screening modalities. Questionnaires were either directly returned by mail orcompleted in-person or over the phone with the help of research staff. Results: Of404 questionnaires that were mailed, 95 (23.5%) were completed. The majority ofsurvey participants were aged 61 to 75 years (78.7%), 48.4% were White, and 38.5%were Black. The highest educational level attained was high school in 48.4%. Self-reported health was good or very good in 68.4%. Most rated their risk of developingCRC as either low or below average (76.7%), but 23.2% knew someone who wasdiagnosed with CRC. Half (52.7%) had previously undergone colonoscopy and41.8% had a prior stool test. Perceptions about barrier and facilitators for colonos-copy and stool testing are shown in Table 1. Notably, 20.0% and 30.9% of individualsresponded they were not offered colonoscopy and FIT in the past 6 months, despitedocumentation to the contrary. The majority of patients (88.6%) indicated that theywould take a blood test for CRC screening. Of those who said they would take theblood test, the perceived advantages over colonoscopy and stool test includedconvenience (59.7%), being accustomed to receiving blood tests (40.3%), and norequirement for special preparation (38.9%, Figure 1). Only 18.1% believed that ablood test had an advantage in terms of accuracy. No significant association wasobserved between demographics, health status, or screening history and willingnessto take a blood test, although sample size was limited. Conclusions: Among patientswho have previously declined colonoscopy and FIT, 89% reported willingness totake a blood test for CRC screening. These data indicate that a blood-based testoffers an opportunity to substantially improve overall screening uptake. Given asubstantial proportion of individuals who do not recall being recently offered colo-noscopy and FIT, these first-line tests should be re-offered before discussing alter-native tests.


ID: 3526661SELF-EXPANDING METAL STENTS FOR THE TREATMENTOF MALIGNANT COLON OBSTRUCTION CAUSED BYEXTRA-COLONIC VERSUS INTRA-COLONICMALIGNANCY – A META-ANALYTIC COMPARISON OFSAFETY AND EFFICACYFaisal S. Ali*, Mohammed R. Gandam, Samreen Khuwaja,Nivedita Sundararajan, Samrah I. Siddiqui, Syeda Naqvi, Sushovan Guha,Nirav Thosani, Maryam R. Hussain, Shahrooz Rashtak, Srinivas Ramireddy,Ricardo Badillo, Tomas DaVeeIntroduction: The relative utility of self-expanding metal stent (SEMS) insertion formalignant colon obstruction (MCO) due to extra-colonic malignancy (ECM) versusintra-colonic malignancy (ICM) is understudied. Methods: A comprehensive searchof Medline (Ovid) and Embase (Ovid) was performed from inception-October 2020.All studies were screened by two authors to identify reports of safety and efficacy of


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SEMS insertion for the treatment of MCO by ECM and ICM. A meta-analysis ofproportions, comparative meta-analysis to compute odds ratios (OR) and meandifferences (MD) with 95% confidence intervals (CIs) were performed. Results: Sixnon-randomized studies enrolling 430 ECM and 439 ICM patients were included,48% (40-57%) and 62% (58-67%) of patients in the ECM and ICM groups were male.ECM patients were younger than ICM (57.73 vs 63: Table 1; MD -4.44; -8.59, -0.30; I279.01%: Table 2). Most obstructions were in the rectosigmoid colon in both ECMand ICM groups. The pooled technical success (TS) of SEMS was similar: 89% (83-96%) in the ECM and 96% (94-98%) in the ICM groups (OR 0.39; 0.10-1.60; I264.66%; Table 2). The clinical success (CS) of SEMS was also similar: 74% (63-86%) inthe ECM and 89% (86-92%) in the ICM groups (OR 0.63; 0.13-3.11; I2 93.19%).Adverse event rate was 29% (16-42%) in the ECM and 15% (12-19%) in the ICMgroup (OR 1.39; 0.54-3.60; I2 83.25%). The most common AE was recurrentobstruction due to tumor in-growth in both ECM (49%; 36-62%) and ICM (53%; 39-66%) groups, followed by SEMS migration (19% (2-35%) in ECM, 22% (13-30%) inICM). Endoscopic reintervention rate was 34% (22-46%) in the ECM and 42% (30-54%) in the ICM group (OR 0.53; 0.19-1.50; I2 29.21%). Surgical intervention ratepost-SEMS placement was 17% (12-21%) in the ECM and 6% (3-9%) in the ICM group(OR 2.76; 0.56-13.58; I2 85.73%). There was no significant difference in stent patency(MD -9.97 days; -59.73, 39.79; I2 98.71%) and overall survival (OS) between the twogroups (MD -120 days; -276.48, 36.27; I2 99.52%). The mean duration of stentpatency was 138.45 days (132.92-143.99) in the ECM and 134.47 (132.26-136.69) inthe ICM group. The mean OS was 127.2 days (121.03-133.38) in the ECM and 177.17days (170.75-183.60) in the ICM group. Conclusion: Clinical outcomes were com-parable after endoscopic stent placement for treatment of both extracolonic andintracolonic malignant obstructions. Although the point estimate of technical andclinical success weighed in favor of intracolonic obstructions, and the point esti-mates of survival and adverse events weighed towards extracolonic obstructions, theconfidence intervals were wide, diminishing potentially significant findings. Theheterogeneity of the data was significant. Future research is needed to furthervalidate these findings.

Table 1 & 2. Meta-Analytic Proportions and Comparison of SEMS for theTreatment of Malignant Colon Obstruction from Intra- and Extra-ColonicMalignancy

Forest Plots of Techincal Success, Clinical Success, Adverse Events, andOverall Survival - SEMS for the Treatment of Malignant Colon Obstructionfrom Intra- and Extra-Colonic Malignancy


ID: 3521766THE IMPACT OF COVID-19 ON TIMELY SURVEILLANCECOLONOSCOPIES IN SOUTH AUSTRALIAMolla M. Wassie*, Madelyn Agaciak, Charles Cock,Graeme P. Young, Erin L. SymondsBackground: The COVID-19 pandemic has affected all elective procedures, includingcolonoscopy, in hospitals worldwide. Delays in surveillance colonoscopies mightincrease the progression of cancer in people at increased risk for colorectal cancer.Limited colonoscopy capacity, as well as patient reluctance to attend hospital, couldlead to colonoscopies not being completed within the appropriate time frame. Thisstudy aimed to determine the impact of COVID-19 on the number of colonoscopiesperformed, the magnitude of delay to surveillance colonoscopies, and whether thepandemic altered patient response to a recall letter for their surveillance colonos-copy in South Australia. Methods: This was a retrospective analysis of surveillancedata during the 3 months (April-June 2020) when colonoscopy services were mostaffected by COVID-19 in South Australia, compared to the three months in 2019(pre-COVID-19). Data on when surveillance colonoscopies were recommended, andresponses to colonoscopy recall letters, were obtained from the public hospitalsurveillance program. Surveillance colonoscopy was defined as delayed if the colo-noscopy was done more than 3 months after the due date based on national rec-ommended surveillance intervals. The c2 test was used to compare percentagesbetween groups (P<0.05 considered statistically significant). Results: During theaudited period in 2020, the total number of colonoscopies completed decreased by51.1% (nZ569), compared to the same months in 2019 (nZ1164). The proportionof urgent category (category 1) colonoscopy procedures increased from 66.8% (746/1117) in 2019 to 86.2% (461/535) in 2020 (p<0.001), accompanied by a decrease inthe number of surveillance colonoscopies done from 371 to 74 (p<0.001). Of 632surveillance colonoscopies due during the audited period, the number of delayedsurveillance colonoscopies increased from 49.8% (162/325) in 2019 to 62.9% (193/307) in 2020 (p<0.001). For the patients �75y sent a letter to consider anothercolonoscopy, in 2020 there were significantly more non-responders (51.6%)compared to that observed in 2019 (23.1%, pZ0.013) however, for responders therewas no difference in the proportion requesting booking. No differences wereobserved in the responses of the patients <75y (p>0.05). Conclusions: Significantreductions and delays in surveillance colonoscopies were seen during the COVID-19pandemic in South Australia, despite a very limited pandemic in this geographiclocation. This occurred due to a reduction in the total number of non-urgent pro-cedures, rather than patient reluctance to have their procedure. These effects arelikely to be much larger in areas affected more by the pandemic. Thus, planning forpost COVID-19 colonoscopy triage and capacity is required to avoid cancer pro-gression in elevated-risk patients due to delays in surveillance colonoscopies.


Abstracts


FRIDAY, MAY 21, 2021Colon and Rectum 1Lecture

ID: 3525121EFFICACY OF COLD SNARE ENDOSCOPIC MUCOSALRESECTION FOR SESSILE SERRATED LESIONSCOMPARED TO ADENOMATOUS LESIONSMatthew Mickenbecker*, Jeevithan SabanathanBackground and Aim: Endoscopic mucosal resection (EMR) with a cold snare isgaining increasing acceptance as an effective therapy for large laterally spreadinglesions in the colon. The cold snare technique offers a favorable risk profile, with lowrates of bleeding, perforation, and post-procedure pain compared to the morewidely used hot snare EMR technique. While there is increasing acceptance of coldsnare EMR for the removal of medium (10-19mm) and large (�20mm) sessileserrated lesions (SSLs), concerns remain about its suitability for the removal ofsimilar sized adenomas. We aimed to study the differences in safety and efficacy ofcold snare EMR for SSLs as compared to adenomas at our institution.Methods: Data was collected retrospectively for EMR procedures of Paris IIa SSLsand adenomas performed at a single centre between 01/02/2018 and 31/05/2020.The Provation endoscopy reporting program was used to source size, morphology,method of resection, and recurrence data. Complications were captured through areview of medical records that included a one-month follow-up phone call. Results:A total of one hundred forty-two eligible EMR procedures were performed over thestudy period (Table 1). The SSLs and adenomas were similarly located throughoutthe colon. One hundred nineteen patients had completed their six-month surveil-lance colonoscopy (SC1) and forty-six their eighteen-month surveillance (SC2). Theoverall recurrence rate at SC1 was considerably lower in the SSL group (3.2% vs14.0%, OR 0.20, P 0.05). The difference was most appreciable in lesions 20mm orlarger (3.1% vs 18.4%, OR 0.14, P 0.08). Recurrence was able to be treated endo-scopically in all cases. There were no complications reported in either group.Conclusion: Our study demonstrates both safety and efficacy of the cold snare tech-nique for medium and large SSLs, while raising concerns about efficacy, but notsafety, for similarly sized adenomas. It is reassuring that recurrence was able to betreated endoscopically in all cases. Considering this and the impressive safety profileof the cold EMR technique, particularly in high risk patients, it may still have a placein the EMR of medium and large adenomas. Further research is required to un-derstand the reasons for this increased recurrence and to determine the optimaltechnique for cold snare EMR of adenomas.


ID: 3521068DEEP SUBMUCOSAL INVASION AS INDEPENDENT RISKFACTOR FOR LYMPH NODE METASTASIS IN T1COLORECTAL CANCER: A SYSTEMATIC REVIEW ANDMETA-ANALYSISLiselotte W. Zwager, Barbara A. Bastiaansen*, Nahid Mostafavi,Roel Hompes, Valeria Barresi, Katsuro Ichimasa, Hiroshi Kawachi,Isidro Machado, Tadahiko Masaki, Weiqi Sheng, Shinji Tanaka,Kazutomo Togashi, Paul Fockens, L. M. G. Moons, Evelien DekkerIntroduction: Accurate risk estimation for lymph node metastasis (LNM) in T1 colo-rectal cancer (CRC) is critical to optimize further treatment. Currently, deep sub-mucosal invasion (DSI) is considered a strong indicator for radical surgery. However,

multiple studies suggest that DSI in absence of other histologic high-risk featuresmight not be a strong predictor for LNM. We conducted a systematic review andmeta-analysis to determine whether DSI is an independent risk factor for LNM in T1CRC. Methods: A systematic search in MEDLINE, EMBASE and Cochrane Library wasperformed from inception to July 2020 (PROSPERO: CRD42020145938). To establishthe risk of DSI for LNM in univariate analysis, all suitable studies were included inmeta-analysis. To determine whether DSI (�1000mm or sm2-3) was an independentrisk factor in relation to other accepted histological risk factors such as poor dif-ferentiation (PD), lymphovascular invasion (LVI) and/or high-grade tumor budding(TB), studies were eligible if 1) DSI was described as the only present high-risk factoror 2) the above-mentioned four main histological risk factors were simultaneouslyincluded in a multivariate analysis. Authors were contacted to provide multivariateanalysis or raw patient data when required. Meta-analysis was performed using arandom-effects model and reported as pooled odds ratio (OR) with 95% confidenceinterval (CI). Results: 59 studies were included comprising in total 19,793 patients.Overall, LNM was present in 11.2%. The number of cases with LNM in univariateanalysis, analyzed in all included studies, was significantly higher in the group withDSI (1,903/12,432; 15.3%) compared to group with superficial invasion (228/4,343;5.2%) (OR 2.73; 95%CI 2.19-3.41). Seven studies (3303 patients) described presenceof DSI in absence of all other high-risk factors. The overall rate for LNM was 2.7%(nZ26/977) resulting in a pooled incidence rate of 0.03 (95%CI 0.02-0.05). Sevenstudies (3515 patients) included DSI in a multivariate analysis in relation to the otherthree risk factors. DSI was the weakest predictor for LNM with an OR of 1.94 (95%CI1.05 – 3.57), compared to PD (OR 2.71; 95%CI 1.70 – 4.32), TB (OR 2.59; 95%CI 1.85– 3.62) and LVI (OR 3.52; 95%CI 2.01 – 6.17). Discussion: Our meta-analysis dem-onstrates that DSI is an independent, but weak predictor for LNM. In DSI cancers,the rate of LNM is low (2.7%) in the absence of other risk factors. In light of theexpanding spectrum of endoscopic resection methods and overtreatment by surgeryfor many patients with T1 CRC, DSI should be reconsidered as strong indicator foroncologic surgery.

FRIDAY, MAY 21, 2021jSATURDAY, MAY 22, 2021Colon and Rectum 1LecturejLecture

ID: 3521647EFFECT OF CLIP CLOSURE ON OUTCOMES AFTERRESECTION OF LARGE SERRATED POLYPS: RESULTSFROM A RANDOMIZED TRIALSeth Crockett*, Mouen A. Khashab, Douglas K. Rex, Ian S. Grimm,Matthew T. Moyer, Heiko PohlBackground: Serrated polyps, particularly sessile serrated lesions (SSL), are impor-tant colorectal cancer precursors. Endoscopic management of serrated polypsoften differs from that of adenomatous polyps due to morphology and other specificendoscopic features. SSLs are most commonly located in the proximal colon, wherepost-polypectomy bleeding rates are higher. There is limited clinical trial evidence toguide best practices for resection of large serrated polyps. Methods: In a multicenterinternational trial, patients with large (�20mm) non-pedunculated polyps removedvia endoscopic mucosal resection (EMR) were randomized to either clipping ofpolypectomy defect or not. This analysis is limited to participants with study polypsthat had serrated histology [SSL, hyperplastic polyps (HP), or traditional serratedadenomas (TSA)], comparing those randomized to clip vs. control group. The pri-mary outcome was severe post-procedure bleeding within 30 days of colonoscopy.Secondary outcomes included risk of other serious adverse events, includingperforation and post-polypectomy syndrome. Frequency of outcomes werecompared between groups using Chi-squared tests. Two tailed p values less than0.05 were considered statistically significant. Results: A total of 195 participants with220 serrated study polyps were included in the study. Polyps included 198 SSLs, 14TSAs, and 8 HPs. The mean age was 63 (SD 9.9), and 53.3% were female (Table 1).39 (20%) participants used antithrombotic medications, including a higher propor-tion in the control vs clip group (26% vs 14%, pZ0.038). Median size of serratedpolyps was 25mm (IQR 20, 30), and the polyps were predominantly located in theright colon (Table 2). 11% of participants had more than 1 qualifying study polyp. 99were assigned to clip closure and 96 were assigned to control. Overall, 7 patients(3.6%) experienced post-procedure bleeding following resection of large serratedpolyps. There was no difference in post-procedure bleeding rates between patientsin the clip vs. control group (4.2% vs 3.0% respectively, pZ0.48). 2 out of 4 patientsin the control group with post-procedure bleeding used antithrombotic medica-tions. 1 patient suffered a perforation and 1 patient had post-polypectomy syn-drome, both in the control group. Conclusion: Results from this clinical trialdemonstrate that the post-procedure bleeding rate for large (�20mm) serratedpolyps removed via EMR is low, and that there was not a clear benefit of prophylacticclipping of the polypectomy defect in this group. Although small sample size is alimitation, this study suggests that endoscopic clipping may not be necessary toprevent post-polypectomy bleeding after resection of large serrated polyps.


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ID: 3524710CHARACTERISTICS OF LARGE COLON POLYPS MISSEDON INDEX COLONOSCOPY IN PATIENTS REFERREDFOR ENDOSCOPIC MUCOSAL RESECTION: ANOBSERVATIONAL STUDYAllen R. Yu*, Philip Kozan, M. Phillip Fejleh, Alireza Sedarat,V. Raman Muthusamy, Stephen KimBackground: Colonoscopy remains the gold standard for colorectal cancerscreening, but missed lesions on screening colonoscopy represent an importantcontributor to the development of interval colorectal cancer. Prior studies haveestimated the prevalence of missed adenomas �10 mm at 2-6%. Methods: This was aretrospective study of all first-time referrals for endoscopic mucosal resection (EMR)of large colon polyps to a tertiary academic medical center over two years. Reports ofthe index colonoscopy, colonoscopy for large colon polyp EMR, and pathology werereviewed for all patients. Patients were included if there was at least one additionalpolyp, besides the lesion being referred, that was greater than 10mm in size iden-tified on the colonoscopy referred for large colon polyp EMR. Information on thesize, location, characteristics, and histology of these additional large polyps wereobtained. A polyp was counted as missed on index colonoscopy if it was found onthe colonoscopy referred for EMR but not documented on the index colonoscopyreport. Results: Among a total of 389 patients referred for EMR of a large colonpolyp, 41 (10.5%) patients had at least one additional large colon polyp. Of these 41patients, 62 additional large colon polyps were identified. 14 of the 62 (22.6%)additional large polyps were missed on index colonoscopy. The average size of the14 missed large polyps was 16.8mm (standard deviation 5.99mm). All missed polypsappeared sessile on endoscopy. A majority of the missed polyps (10 of 14, 71.4%)were located in the right colon. Despite their sessile appearance, most of the missedpolyps (12 of 14, 85.7%) were classified histologically as tubular or tubulovillousadenomas and not as sessile serrated adenomas. None of the missed polyps wereclassified as adenocarcinoma on final pathology. Conclusions: In patients beingreferred for large colon polyp EMR, additional large colon polyps may be overlookedat time of index colonoscopy. Most of these missed polyps are sessile and located inthe right colon. Interventional endoscopists should be cognizant of the possibility offinding additional large colon polyps in these high-risk patients.


ID: 3520136RISK OF METASTATIC RECURRENCE AFTERADDITIONAL SURGERY IN RELATION TO THE VERTICALTUMORMARGIN OF ENDOSCOPIC RESECTION FOR T1BCOLORECTAL CARCINOMATomoyuki Nishimura*, Shiro Oka, Yuki Kamigaichi, Hirosato Tamari,Yasutsugu Shimohara, Yuki Okamoto, Katsuaki Inagaki, Kenta Matsumoto,Hidenori Tanaka, Ken Yamashita, Yuki Ninomiya, Yasuhiko Kitadai,Shinji TanakaBackground and purpose: We previously reported that preceding endoscopicresection (ER) for T1 colorectal carcinoma (CRC) requiring additional surgery hadno effect on patient’s prognosis (J Gastroenterol 2019). In addition, the JapaneseSociety for Cancer of the Colon and Rectum stated that the vertical tumor margindistance (the distance from the deepest invasion portion of carcinoma to themarginal termination resected by ER) of 500 mm or more is desirable for ER toreduce lymph node (LN) metastases. We analyzed the influence of vertical margindistance of ER for T1b (submucosal invasion > 1000mm) CRC on the metastaticrecurrence and prognosis of patients who underwent additional surgery afterER.Method: A total of 215 consecutive patients with T1b CRC who underwentadditional surgery after ER at Hiroshima University Hospital between February 1992and June 2019 were enrolled. There were 105 patients who underwent resection byendoscopic submucosal dissection and 110 patients by endoscopic mucosalresection. We assessed 191 patients without LN metastases after additional surgery(average follow-up period, 73 months). Vertical margin distance of resectedspecimens by ER was classified into three groups: 104 patients with vertical margindistance of 500 mm or more (Group A), 43 patients with vertical margin distance ofless than 500 mm (Group B), and 44 patients with vertical tumor margin positive(Group C). We analyzed the clinicopathological characteristics and prognosis of T1bpatients among the three groups. Results: There were no significant differences inage, sex, tumor size, localization, gross type, main histology, lymphatic invasion,venous invasion, and budding grade among the three groups. Metastatic recurrencefor each group was as follows: Group A (0%), Group B (11.6%; 2 lungs, 1 liver/lung


Abstracts


and 2 pelvic LNs; average period to recurrence is 26 months), and Group C (9.1%; 1liver/lung, 1 liver and 2 lungs; average period to recurrence is 31 months). The 5-yearoverall survival rate was 98.7% in Group A, 93.8% in Group B, and 95.5% in Group C;there was no significant difference among the groups. The recurrence-free 5-yearsurvival rate was 100% in Group A, 84.5% in Group B, and 81.8% in Group C. GroupA had a significantly higher rate than Group B (pZ0.0006) and Group C(pZ0.0003). The disease-specific 5-year survival rate was 100% in Group A, 97.4% inGroup B, and 95.5% in Group C; group A had a significantly higher rate than GroupC (pZ0.0313). Conclusions: Complete en bloc resection with sufficient submucosallayer (vertical section distance >500 mm) by ER is necessary in patients with T1b CRCto reduce the risk of metastatic recurrence after additional surgery.

FRIDAY, MAY 21, 2021jSATURDAY, MAY 22, 2021Colon and Rectum 1LecturejLecture

ID: 3523387EFFICACY OF REAL-TIME COMPUTER AIDEDDETECTION OF COLORECTAL NEOPLASIA IN A NON-EXPERT SETTING: A RANDOMIZED CONTROLLED TRIALAlessandro Repici, Marco Spadaccini*, Giulio Antonelli, Roberta Maselli,Piera Alessia Galtieri, Gaia Pellegatta, Antonio Capogreco,Sebastian Manuel Milluzzo, Gianluca Lollo, Elisa Chiara Ferrara,Alessandro Fugazza, Silvia Carrara, Andrea A. Anderloni, Arnaldo Amato,Andrea De Gottardi, Cristiano Spada, Franco Radaelli, Cesare HassanBackground & aims: One-fourth of colorectal neoplasias are missed duringscreening colonoscopies; these can develop into colorectal cancer (CRC). Severaldeep learning based real-time computer-aided detection (CADe) systems provedtheir efficacy in improving the performance of expert endoscopists in neoplasiadetection. We performed a multicenter, randomized trial to assess the efficacy of aCADe system in detection of colorectal neoplasias in a non-expert setting tochallenge the CADe impact in a real-life scenario. Methods: We analyzed data ofconsecutive 40- to 80-years-old subjects undergoing screening colonoscopies forCRC, post-polypectomy surveillance, or workup due to positive results from a fecalimmunochemical test or signs or symptoms of CRC, at 5 European centers from Julythrough September 2020. Endoscopists with a previous experience of <1500 colo-noscopies performed all the exams. Patients were randomly assigned (1:1) to groupswho underwent high-definition colonoscopies with the CADe system or without(controls). As CADe, we used a convolutional neural network with convolutional andmax pooling layers (GI-Genius, Medtronic) that was integrated in the endoscopysystem (i.e. real-time output on the same endoscopy monitor). A minimum with-drawal time of 6 minutes was required. The primary outcome was adenoma detec-tion rate (ADR, the percentage of patients with at least 1 histologically provenadenoma or carcinoma). Secondary outcomes were adenomas detected per colo-noscopy, and withdrawal time. Results: The final analysis included 660 patients (age:62.3�10.0 years old; gender M/F: 330/330). ADR was statistically significantly higherin the CADe-group (176/330, 53.3%) than in the control group (146/330, 44.2%; OR:1.44; 95% CI:1.06 to 1.96), as well as APC (1.26; 95% CI:1.14-1.38 vs 1.04; 95%CI:0.93-1.15; incident rate ratios, IRR:1.21; 95% CI:1.05-1.40). No statistically signif-icant difference in withdrawal time (CADe: 8.1�1.61 minutes vs control: 7.9�1.53;pZ0.06) was observed. Conclusions: In a multicenter, randomized trial, we foundthat including CADe in real-time colonoscopy significantly increases ADR and ade-nomas detected per colonoscopy in a non-expert setting.

SATURDAY, MAY 22, 2021Colon and Rectum 1Poster

ID: 3524723REFERRAL TRENDS IN ENDOSCOPIC MUCOSALRESECTION OF COLON POLYPS: A COMPARISON OFTWO TIME PERIODSPhilip Kozan*, Allen R. Yu, M. P. Fejleh, Alireza Sedarat,V. Raman Muthusamy, Stephen KimIntroduction: Endoscopic mucosal resection (EMR) has emerged as a cost-effectiveand safe technique for removing large colon polyps with a lower risk of complica-tions as compared to surgery. With the rise of colon polyp referrals, it is important tounderstand the trend in types of polyps that are referred for EMR. Methods: Aretrospective chart review was performed to identify patients who underwent anindex colonoscopy and were referred for colon polyp EMR with interventional en-doscopists at a single tertiary academic center over two separate academic years(2014-2015 vs. 2018-2019). Our primary outcome was to determine if there was adifference in colon polyp size referred for EMR between the two time periods.Secondary outcomes were differences in location, pathology and total additional

polyps between each academic year. Statistical analysis was performed with Welch’st-test and Chi-square test. Results: A total of 389 patients were referred for EMR oflarge and complex colon polyps that were not removed at index colonoscopyincluding 122 patients in 2014-2015 and 267 patients in 2018-2019. Among the twogroups, a total of 129 polyps and 337 polyps were identified and removed, respec-tively. There were no significant differences in the age, gender and race amongpatients referred in the two time periods. There was no statistically significant dif-ference in the size of the colon polyps identified on EMR. However, there was atrend towards significance in the number of polyps referred that were <15 mm insize when comparing 2018-2019 vs. 2014-2015 (nZ 98 vs. 36, pZ 0.065). There wasno difference in the anatomic location of the referred colon polyps. There was atrend towards significance in the type of pathology of the colon polyp with an in-crease in sessile serrated adenoma/polyps in 2018-2019 vs. 2014-2015 (n Z 85(25.2%) vs 19 (14.7%), p Z 0.064). A significant increase in patients referred forlarge colon polyp EMR had at least 2 or more polyps found on subsequent colo-noscopy when comparing 2018-2019 vs. 2014-2015 (n Z 48 vs. 6, p < 0.001).Discussion: In patients referred for colorectal polyp EMR, there is a growing trendthat patients are more likely to have additional colon polyps at the time of repeatcolonoscopy. While the overall colon polyp size has not changed, there may be anincreasing number of smaller polyps and sessile serrated adenoma/polyps that arebeing referred for EMR. Given this trend, interventional endoscopists may considerbooking adequate time to account for the possibility of finding additional advancedadenomas.


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ID: 3527156EXPERIENCE OF ENDOSCOPIC SUBMUCOSALDISSECTION FROM SINGLE TERTIARY CENTER FORCOLORECTAL NEOPLASMS: CHARACTERISTICS,OUTCOMES, AND RECURRENCESakolwan Suchartlikitwong*, Nael Haddad, Paul A. Muna Aguon,Kelly Zucker, Brian M. Fung, Mahmoud Bayoumi, Anam Omer,Teodor C. PiteaIntroduction: Endoscopic submucosal dissection (ESD) has been introduced as aminimally invasive approach to remove large colorectal mucosal lesions, suspectedfor advanced histology. Moreover, this procedure has replaced a surgical resectionfor the treatment of early colorectal neoplasms in some experienced centers. Thereare still a few data on long-term outcomes, recurrence, and complications after ESD.Method: We performed a retrospective chart review of patients who underwent ESDto remove colorectal mucosal lesions between January 2015 and November 2020from a university referral center in Phoenix, Arizona. The procedure was performedby a single advanced-endoscopist. Data collected from medical records wereanalyzed by using Student’s t-test and chi-square. Statistical significance was definedas p-value < 0.05. Result: There were 49 patients, 57% male and 43% female, whounderwent ESD for colorectal mucosal lesions at our center from January 2015 toNovember 2020. The mean age was 67.4 years. The mean lesion size was 31.9 mm.The median procedure time was 93 minutes. Locations of ESD were at right colon(6.1%), transverse (12.2%), and left colon (81.6%). There were 22.4% (11/49) ofhigh-grade dysplasia adenomas and 26.5% (13/49) of adenocarcinoma. En- blocresection was done in 41 cases (83.7%), whereas 8 cases (16.3%) had a completeresection by using snare due to large size and difficult locations. Out of 49 patients,27 (55%) had follow-up endoscopy at our center. The mean follow-up time was 15.3months. Local recurrence was found in 3 patients (11.1%). Among advanced his-tology lesions (high-grade dysplasia and adenocarcinoma), 50% involved submu-cosa. R0 resection, defined as negative deep and lateral margin, was achieved in 85%of advanced lesions. Patients, who had adenocarcinoma with a positive deep margin,were referred to oncology for chemoradiation. All of them had no local recurrence atthe time of follow-up endoscopies with the longest follow-up of 3 years. Post-ESDcomplications were 12.2% for delayed bleeding and 2% for micro-perforation whichwere treated successfully with endoscopic interventions. Conclusion: Endoscopicsubmucosal dissection (ESD) of colorectal neoplasms has favorable outcomes andsafety profile. Complete resection of early-stage colorectal cancer can be achievedwith a high rate. When combined with adjuvant chemoradiation and vigilant colo-noscopy surveillance, patients can remain in remission for many years.


ID: 3523296COMBINED FORWARD AND RETROFLEXIONWITHDRAWAL DURING COLONOSCOPY USING ASECOND-GENERATION SHORT-TURN RADIUSCOLONOSCOPECarlos Robles-Medranda*, Roberto Oleas, Juan M. Alcívar-Vásquez,Carlos Cifuentes, Haydee Alvarado, Raquel S. Del Valle,Miguel Puga-Tejada, Ariana C. Lopez Acosta, Hannah P. LukashokIntroduction: Colonoscopy is the screening method to prevent colorectal cancer;however, polyps and adenomas are missed indivertibly. Factors such as the loca-tion of polyps on difficult areas (proximal side of the ileocecal valve, haustral folds,flexures, or rectal valves). We aimed to evaluate the impact of combined forward andretroflexion withdrawal using a second-generation short-turn radius colonoscopeduring colonoscopy. Methods: a non-randomized, single-center prospective trial.Patients were submitted first to a standard high-definition screening colonoscopy.Then, a second procedure on the same patient combining forward and retroflexionwas performed by a different operator. Lesions detected on the second procedurewere considered as originally missed during standard colonoscopy. We calculatedthe polyp detection rate and the adenoma detection rate of both standard andcombined colonoscopy techniques. Statistical analysis was performed on R.4.0.3.Results: A total of 203 patients were included for analysis. The median age was 57years, 66% were female. The reason for colonoscopy was diagnostic on 81.3%,screening on 15.8%, and 3.0 % for surveillance. Regarding the size of the lesions,74.5% of lesions detected on forward-viewing were < 5 mm. Whereas, on retro-flexion 65.3% sized < 5mm and 34.7% between 5-10 mm. The polyp detection ratefor forward-viewing colonoscopy was 39.90. The polyp detection rate for combinedforward and retroflexion colonoscopy was 54.18. The adenoma detection rate for

forward-viewing colonoscopy was 21.18. The adenoma detection rate for combinedforward and retroflexion colonoscopy was 32.01. Conclusion: We found that com-bined forward and retroflexion withdrawal technique during colonoscopy increasesthe polyp and adenoma detection rates in comparison to standard colonoscopy.Larger, multi-center trials are necessary to validate these data.


ID: 3524071SELF-EXPANDING METALLIC COLORECTAL STENTPALCEMENT GUIDED BY ULTRA-FINE ENDOSCOPE: ASINGLE CENTER’S RETROSPECTIVE STUDY.Jun Li*, Yao-Peng ZhangAim: Self-expanding metallic stent (SEMS) placement has been recommended formalignant colorectal obstruction. Due to the limitation of conventional colonoscope(which diameter was usually more than 1cm), the technical failure rate is 2% to 10%.However, the ultra-fine endoscopy can easily see the obstructive lesions directly andreach the proximal colon through the narrow segment in most cases. The aim of thisstudy was to verify the effectiveness and safety of stent placement guided by ultra-fine endoscope which diameter was 5.0 mm (Fujifilm EG-530N, Tokyo, Japan).Methods: The data of patients with malignant colorectal obstruction treated byendoscopic colorectal SEMS implantation in the Peking University Third Hospitalfrom June 2018 to November 2020 were retrospectively analyzed. According to thetechnical details, patients were divided into conventional colonoscope group (co-lonoscope group) and ultra-fine endoscope group (ultra-fine group). Gender, age,lesion location, maximum diameter, angle between endoscope and lesion (0�, < 90�and �90�) were compared respectively. The time of inserting guidewire ( fromreaching the obstruction site to the guidewire passing through the obstruction) andthe whole operation time (from reaching the obstruction site to releasing the stent)and complications were observed. Results: A total of 47 patients were included in thestudy, including 11 patients in the ultra-fine group (male 6 cases, female 5 cases) and36 patients in the colonoscope group (male 25 cases, female 11 cases) . The averageage of the two groups was 61.7�13.9 year-old vs. 69.9�15.0 year-old (P Z0.112).There was no significant difference in the site and the diameter of the lesions. Theangle between the endoscope and the obstruction was less in the ultra-fine group(10 in 0�, 1 < 90� and 0�90�) than in the colonoscope group (8 in 0�, 26 < 90� and 2�90�) (PZ0.000). The time of inserting guidewire was significantly shorter in theultra-fine group (2.8�3.1 min) than in the colonoscope group (12.0�7.9 min)(PZ0.01). However, there was no significant difference between the whole opera-tion time (17.7�13.3 min vs.24.1�11.0 min, PZ0.120). No complications neededemergent treatment such as bleeding and perforation occurred in both groups.There was one case of stent falling off in the colonoscope group. In the ultra-finegroup, a penetrating ulcer was found on surgical specimen in one case two weekslater, but the patient had no symptoms. Conclusion: Guidewire placement guided byultra-fine endoscope was more quickly with higher success rate. However, as thestent can not be passed through the ultra-fine endoscope, the ultra-fine endoscopehas to be withdraw before the SEMS was inserted. It is necessary to further optimizethe procedure and shorten the overall operation time. The safety of SEMS place-ment under ultra-fine endoscopy is also very good.

Table. Charicteristics of patients in ultra-fine group and colonoscopegroup.


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ID: 3526168DON’T GIVE UP ON THEM YET: OLDER AGE ISASSOCIATED WITH ADVANCED NEOPLASIA ATSURVEILLANCE COLONOSCOPYBryant Megna*, Aaron Boothby, Amy Gravely, Zhuo Geng, Aasma ShaukatBackground: Colorectal cancer (CRC) incidence andmortality have improved over thepast decades, largely due to increased rates of CRC screening and subsequent sur-veillance colonoscopy, with the aim of detecting advanced neoplasia (AN) and CRC.Whether older individuals (age 70+)benefit from surveillance colonoscopy taking intoaccount size, number and location of AN at baseline colonoscopy is not known. Ourstudy aims were to assess the risk factors for advanced neoplasia at surveillance colo-noscopy by age cohorts given the current interest in decreasing surveillance. Methods:We collected information from a cohort of U.S. veterans at a single center (nZ932)that had undergone two colonoscopy exams at least 6 months apart between 2010and 2019. Univariate analysis was performed on clinical, endoscopic, and providerpredictors associated with developing interval AN. Variables demonstrating athreshold of p<0.2 were promoted to a multivariate logistic regression. Specific testsof significance included two sample t-test (quantitative/continuous) and Pearson’sChi-square (categorical). A Kaplan-Meier curve was created to illustrate time-to-event. Results: Demographic and baseline characteristics of patients found to haveAN on follow up colonoscopy compared to those without are depicted in Table 1.On multivariable regression, older age was the strongest predictor of AN on followup colonoscopy, with an approximate 3.2% increase in odds per year (OR [per unittime] 1.032, 95%CI: 1.0079-1.0571, p<0.001). Time to follow up colonoscopy wasalso associated with risk of AN (OR 1.2, 95% CI: 1.0955-1.3164 xx; p <0.0001) .Modifiable risk factors such as high body mass index (BMI) and smoking status didnot influence rate of AN at surveillance colonoscopy. Further, provider adenomadetection rate, index adenoma size, total adenoma burden, and dysplastic histologywere not predictive of AN at surveillance colonoscopy. Time-to-event (developmentof AN) analysis stratified by age above or below 70 (Log-rank, p<0.0001) is presentedin Figure 1. Conclusions: Older age and time to surveillance colonoscopy are thestrongest risk factors for AN in follow up colonoscopy. Adenoma size, location,number or lifestyle risk factors did not influence risk of AN at follow up colonoscopy.Our work suggests continuing timely surveillance in older individuals.

Table 1. Demographic and baseilne patient characteristics.

Figure 1. Kaplan-Meier curve depicting probability of advanced neoplasia(AN) on surveillance colonoscopy, stratified by patients older and youngerthan 70 years.


ID: 3521049RISK FACTORS OF ADVANCED COLORECTAL POLYPWITH SMALL AND INTERMEDIATE SIZE ININDIVIDUALS YOUNGER THAN 50 YEARS OLDChun-Wei Chen*, Wey-Ran LinIntroduction: Colonoscopy screening for colorectal neoplasm is recommended atthe age of 50 years old. Limited data on the characteristics of colorectal neoplasmless than 50 years old is available. The aim of this study is to investigate the char-acteristics of colorectal neoplasm and identify the risk factor of advanced colonpolyp in individuals less than 50 years old. Patients and methods: This study wasperformed in a teaching medical center of northern Taiwan. From Jan, 2015 to Jan,2017, patients who performed polypectomy with polyp size between 6 to 20 milli-meters and younger than 50 years old were enrolled in this study. The demographyof patients and the polyp characteristics including polyp pathological findings, size,location and morphology were collected. Descriptive statistics and frequency werecalculated. Univariate and multivariate logistic regression analyses were performedfor the risk factors of polyp with villous component and high grade dysplasia. Sta-tistical significance was defined as p value < 0.05. Results: A total of 264 patients with323 polyps were included in this study. The male patients were 183 (69.3%). Thedemography of patients and polyps were listed in Table 1. In advanced colorectaladenoma, there were 171 (52.9%) polyps � 10 mm, 58 (18%) polyps with villouscomponent and 2 (0.6%) polyps with high grade dysplasia. In multivariate analysis,the polyp size with increasing 1 mm and pedunculated shape were associated withvillous component and high grade dysplasia in patients younger than 50 years old(Table 2). For polyp sized � 10mm, the pedunculated shape was the only risk factor(ORs: 7.62, 95% CI: 3.32-17.49, p <0.001). Conclusions: Increased polyp size andpedunculated polyp shape are the independent risk factors of advanced colorectalpolyps in individuals younger than 50 years old.


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Table 1. Baseline clinical characteristics of the enrolled patients

Table 2. Logistic regression analysis for villous component and highgrade dysplasia


ID: 3523886LONG-TERM OUTCOMES AND SURVIVAL AFTERENDOSCOPIC OR SURGICAL RESECTION FOR T1COLORECTAL CANCER: A MULTICENTERRETROSPECTIVE STUDYHirohito Tanaka*, Shiko Kuribayashi, Masanori Sekiguchi, Atsuo Iwamoto,Yoko Hachisu, Yasumori Fukai, Tetsuo Nakayama, Kensuke Furuya,Tomoyuki Masuda, Kazuhiro Takahashi, Kyoko Marubashi, Toshio UraokaIntroduction: According to the American Gastroenterological Association (AGA)guidelines, the curative criteria of endoscopic resection (ER) for T1 colorectal can-cer (CRC) are well/moderately differentiated adenocarcinoma or papillary carci-noma, no lympho-vascular invasion, submucosal invasion depth <1000mm, andbudding grade (BD) 1. Although an additional surgery is recommended for non-curative ER, the incidence of lymph node metastasis (LNM) is less than 12%. Somepatients do not undergo surgery due to their old age and perspective in clinicalpractice, their clinical outcomes are not fully evaluated. Aims ＆ methods: The aimof this study was to clarify clinical outcomes in patients with T1 CRC. A total of 471consecutive patients were enrolled from April 2009 to August 2019 at 10 institutions.Exclusion criteria included evidence of familial adenomatous polyposis, hereditarynonpolyposis colorectal cancer, or inflammatory bowel disease; presence of active,malignant diseases in any other organs; presence of synchronous or metachronousadvanced CRC. Risk factors of LNM and recurrence, and survival were analyzed.Results: The mean age of patients was 68.5�10.6 years. The location of the lesionwas 320(67.9%) and 151(32.1%) in the colon and rectum, respectively. A numberof patients with ER without additional SR (ER alone) were 149(curative resection 74,non-curative resection 75), those with SR (SR alone) were 242, and those with ERand additional SR (ER + additional SR) were 80. (i) Risk factor of LNM: LNM wasfound in 10(12.5%) patients with ER + additional SR and in 34(14.2%) patients withSR alone. In multivariate analysis, positive lymphatic invasion was the only significantindependent risk factor for LNM (OR 8.8, 95% CI [2.78-28.2], p<0.01). (ii) Recur-rence: During the mean observation period of 1188�927 days, recurrence was foundin 14(3.0%) patients. No recurrence was found in the ER curative resection group.Although 48% (75/155) patients with ER non-curative resection did not receiveadditional SR, there was no significant difference in recurrence rate between ERalone with non-curative resection and ER + additional SR groups (5.3% (4/75) vs.2.5% (2/80), respectively; pZ0.43). In the SR alone group, recurrence was found in3.3% (8/242). The significant independent risk factor for recurrence was BD 2/3 (OR6.1, 95% CI [1.17-31.8], p<0.01). (iii) Survival: There were 17 deaths during theobservation period, but CRC-related death was found in only 2 cases (0.42%); onewas ER alone with non-curative resection and the other was SR alone. Conclusion:This study suggests that the possibility of expanding the indication for ER of T1 CRC,because positive lymphatic invasion was the only risk factor for LNM and better long-term outcomes were shown despite including significant number of patients with ERalone with non-curative resection.


ID: 3524880COMPARISON OF RISK OF METACHRONOUS LESIONSBY PRESENCE OF A SESSILE SERRATED LESION AMONGINDIVIDUALS WITH ADENOMA ON INDEXCOLONOSCOPYSeung Wook Hong*, Ha Won Hwang, Dae Sung Kim, Jiyoung Yoon,Jin Wook Lee, Sang Hyoung Park, Byong Duk Ye, Jeong-Sik Byeon,Seung-Jae Myung, Suk-Kyun Yang, Jeongseok Kim, Dong-Hoon YangBackground & Aim: Surveillance guidelines suggest the interval of colonoscopy bystratifying the risk based on findings in index colonoscopy. However, the risk ofmetachronous lesions on the coexistence of adenoma and sessile serrated lesion(SSL) was rarely addressed. We aimed to evaluate the impact of the presence ofsynchronous SSL on the risk of metachronous lesions within a similar adenoma riskgroup. Methods: We retrieved individuals with at least one more adenoma on indexcolonoscopy and they were stratified into four groups depending on the presence ofSSL and low-risk/high-risk adenoma (LRA/HRA) on index colonoscopy. Subjects whoundertook a surveillance colonoscopy at least 12 months apart were included in theanalysis. We compared the risk of metachronous lesions including HRA, advancedadenoma (AA), or SSL within a similar adenoma risk group by the presence of SSL.Results: A total of 4,493 individuals were eligible for the analysis. The risk of meta-chronous HRA/AA had not increased significantly in the adenoma plus SSL groupcompared with isolated adenoma group, irrespective of LRA (HRA, 6/86 vs 231/3,297,


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pZ1.00; AA, 0/86 vs 52/3,297, pZ0.64) or HRA (HRA, 11/64 vs 240/1,046, pZ0.36;AA, 3/64 vs 51/1,046, pZ1.00). However, the risk of metachronous SSL in individualswith synchronous SSL had significantly increased compared with those without SSLboth in LRA (15/86 vs 161/3,297, p<0.001) and HRA (11/64 vs 61/1,046, pZ0.002).Conclusions: The presence of synchronous SSL does not increase the risk of meta-chronous HRA/AA compared with isolated adenoma but increased the risk ofmetachronous SSL.

Figure 1. Eligible individuals flow diagram.

Table 1. Comparison of risk of the metachronous lesion by the presenceof a sessile serrated lesion on index colonoscopy


ID: 3523875POST-POLYPECTOMY BLEEDING WITH PROPHYLACTICCLIPS: EAST MEETS WESTBenjamin D. Renelus, Devika Dixit*, Daniel S. JamoraboBackground: The rate of post-polypectomy bleeding (PPB) per colonoscopy is0.44%. Studies have shown that PPB rate is affected by polyp size and colon loca-tion, but there has been no comparison between population regions. We sought toinvestigate the PPB difference when prophylactic clips were employed post-poly-pectomy between East- and West-based populations. Methods: We performed asystematic search of PubMed/Medline and Scopus databases for randomizedcontrolled trials investigating the difference in PPB when polypectomy was under-taken with and without prophylactic clipping. Our primary endpoint was PPB dif-ference with prophylactic clips between Western hemisphere (West) and Easternhemisphere (East) populations. Our secondary endpoint was overall PPB differencebetween use of post-polypectomy clipping versus no clipping. To evaluate the pri-mary endpoint, we generated a bubble plot meta-regression (Figure 1). We alsoperformed a meta-analysis with fixed and random effects models to establish pooledrelative risk estimates using Mantel-Haenszel and Dersimonian-Laird methods,respectively. Forest plot with relatively risk (RR) and 95% confidence intervals (CI)were likewise developed (Figure 2). Results: Two West-based studies and five East-based studies including 4,687 polyps were included for analysis. When compared toEastern populations, there was a trend toward significant reduction in PPB with useof prophylactic clips for Western populations (RR 0.53; 95% CI 0.28-1.02; pZ0.058).There was no overall difference in PPB based on whether or not post-polypectomyclipping was undertaken (RR 0.83; 95% CI 0.59-1.16; pZ0.40). Conclusion: There is

an insignificant trend towards reduced PPB with post-polypectomy clipping inWestern populations compared to Eastern populations. Overall, we did not find thatprophylactic clip placement reduced the risk for PPB.


ID: 3523446TECHNICAL OUTCOMES AND RISK OF STRICTUREAFTER ENDOSCOPIC SUBMUCOSAL DISSECTION FORLARGE COLORECTAL LESIONSMaselli Roberta, Marco Spadaccini*, Piera Alessia Galtieri, Gaia Pellegatta,Elisa Chiara Ferrara, Alessandro Fugazza, Silvia Carrara,Andrea A. Anderloni, Alessandro RepiciBackground & aims: Endoscopic submucosal dissection (ESD) is a well-establishedapproach for the minimally invasive treatment of colorectal (CR) neoplasia withfavorable outcomes in term of efficacy and safety. Although technical improvementsenable en-bloc removal of large circumferential and near-circumferential rectallesions, the efficacy outcomes, as well as the incidence of strictures and otheradverse events after rectal ESD, have only been described in few Eastern countries’experiences. The aim of this study is to assess efficacy and safety outcomes of acohort of patients treated with ESD for large rectal lesions in a tertiary Westerncenter, with a particular focus on the risk of stricture. Methods: Between February2011 and June 2019, a retrospective analysis of a prospectively maintained databasewas conducted on patients treated by ESD for large rectal lesions that required�75% circumferential resection at Humanitas Research Hospital in Milan, Italy. Theprimary outcome considered for this study was the risk of stricture. Secondaryoutcomes were en-bloc, and R0 resection rates, procedural time, and other adverseevents. The curative resection rate was assessed for submucosal invasive lesions.Results: Over the study period, 213 consecutive patients underwent a rectal ESD.Eighty-eight of them (mean age: 68.5�12.9 years old; 50 -56.8%- males) required� 75% circumferential resection (32 circumferential resection) and were included inthe study analysis. The 94.3% of lesions were resected in an en-bloc fashion in amean procedural time of 110.6�63.2 min. The rate of R0 resection was 80.7%.Eighteen out of 88 lesions (20.5%) resulted in CR neoplasia with submucosal inva-sion. Eight of them (44.4%) showed high-risk features of nodal involvement (non-curative resection) and were referred for surgery. A total of 3 (3.4%) peri-proceduralAEs (2 intraprocedural bleedings, 1 post-procedural perforation) occurred. Post-ESD


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rectal strictures occurred in 4 out of 80 patients (5.0%), being strictly associated tocircumferential resections (4/32, 12.6%). The 4 patients underwent endoscopicballoon dilation with symptoms resolution. Conclusion: Rectal ESD is a safe andeffective option for managing large rectal neoplasia in a Western setting. The risk ofpost-procedural stricture is associated to circumferential resections, and patientsshould be aware of the possible need of endoscopic dilations.


ID: 3522208THE FEASIBILITY OF COLORECTAL ENDOSCOPICSUBMUCOSAL DISSECTION ON LESIONS WITH SCARTISSUE: A RETROSPECTIVE STUDY IN A SINGLETERTIARY CARE MEDICAL CENTER IN THE UNITEDSTATESNiranjani Venkateswaran*, Justin Roy, Ji-Min Park, Matthew T. Moyer,Mathew AbrahamIntroduction: Endoscopic submucosal dissection (ESD) is a minimally invasive tech-nique that enables en bloc resection of early gastrointestinal tumors and precan-cerous lesions, however, it is not widely used in the colon due to the thinner colonicwall, higher complication rates, and efficacy and safety of standard endoscopicmucosal resection (EMR). Limited data on colorectal ESD has been published in theUnited States. The purpose of this study is to determine the safety and efficacy ofusing colorectal ESD in both scar-embedded and non-scarred colorectal lesions in asingle US tertiary care center. Methods: A retrospective chart review betweenJanuary 2013 and April 2020 identified 159 patients who had undergone colorectalESD for en bloc resection due to the appearance of advanced pathology such asNICE 3, nongranular section, or Paris IIc; scarred lesions not amenable to standardEMR or a failed EMR attempt. The primary outcome was en bloc resection ratesbetween scarred and non-scarred colorectal lesions among lesions that were notamenable to EMR. Our secondary outcomes were tumor recurrences at 6-monthfollow-up and serious adverse events within 30 days. Results: Out of 159 colorectalESD procedures, the mean lesion size was 25.86 � 16 (15.86 - 41.86) mm, with anaverage procedure time of 97 � 67 (30-164) minutes. Overall, the en bloc resectionrate was 52.2% (83/159) and the R0 resection rate among the “non-scarred and enbloc lesions” was 41.3% but total of 49% (78/159) were unknown. Among the lesionsthat were “not amenable to EMR”, en bloc resection was achieved in 64% (29/45) ofthe scarred lesions, and 60.5% (46/76) of the non-scarred lesions (p Z 0.66). Lesionsthat were malignant or had high grade dysplasia were 36.4% (58/159). Follow-upcolonoscopy was performed at a mean of 5.03 � 5 months, which was completed in73.5% (117/159) of the cases. About 3.41% (4/117) had tumor recurrences in which 3of them proceeded with surgery. In total, there were 6 perforations (3.7%), with 1requiring emergent surgery but no mortalities. Major bleeding event was 1/159(0.63%). Conclusion: Our study showed an overall lower en bloc and R0 resectionrates compared to eastern countries. Our limitation with low R0 resections could bepossibly due to the inadequate margin surrounding the tumor. Although previousliterature including meta-analysis suggest fibrosis as one of the limiting factors in enbloc resections, we found no statistically significant difference between scarred andnon-scarred lesions. Despite this, colorectal ESD demonstrated a reasonable successrate with a recurrence rate of < 5% and was found to be relatively safe given aperforation rate of 3.7%, and no fatalities. While this is promising, further multi-center studies with a larger sample size are needed to better characterize theviability of colorectal ESD in the United States.

Figure 1. Pre and Post ESD intervention of both scarred and non-scarredcolorectal lesion.


ID: 3518085PREDICTING COLORECTAL ADENOMA AND ITS RISKFACTORS IN AFRICAN AMERICAN DOMINANT PATIENTPOPULATIONHamid-Reza Moein*, Salina Faidhalla, Hersimren Minhas, Mahvish Khalid,Paul H. Naylor, Bashar MohamadIntroduction: Colorectal adenomas are precursors of colorectal cancer (CRC). There-fore, an optimal CRC prediction model should have the ability to predict adenomas.We aimed to identify risk factors for colorectal adenomas in African Americandominant patient population. In addition, we tested whether previously validatedclinical scores for CRC or adenoma detection can correctly predict the risk ofidentifying adenomas prior to colonoscopy. Methods: A retrospective, case-control,chart review study. From a total of 1095 patients who had colonoscopy in the last 6months of 2017, 52 patients with advanced adenoma (�1cm, or high grade tubulo-villous or villous, or high-grade dysplasia) were identified. Two age- and gender-matched controls were used as comparators. Patients with low-risk adenoma (i.e.,<1cm, and no high-risk histologic features) and no adenoma were served as positiveand negative controls, respectively. BMI, past medical history, family history, socialhistory, use of aspirin and NSAIDs in past 30 days, and hormone therapy were re-corded as potential risk factors of CRC. QCancer (http://qcancer.org/15yr/colorectal)was used to calculate the risk of CRC. Advanced adenoma detection risk is calculatedbased on a validated formula from university of Minnesota (Gastroentrol HepatolIntJ 2017,2(1):00017). Results: 156 age- and gender-matched patients were analyzed(52 patients in each group). Total of 89.7% African American and 10.3% Caucasianwere included. There was no significant difference in age and gender among 3groups. Interestingly, among the evaluated risk factors, only chronic obstructivepulmonary disease (COPD) was more prevalent among advanced adenoma patientsas compared to no adenoma (18.18% vs. 1.96%; pZ0.01). Mean 5-year CRC calcu-lated risk was 0.55�0.06%, 0.40�0.03%, and 0.50�0.05% in advanced adenoma, low-risk adenoma, and no adenoma groups, respectively (pZ0.11). Similarly, there wasno significant difference in the mean15-year CRC risk among 3 groups (2.38�0.26%,1.78�0.13%, and 2.20�0.22%, respectively; pZ0.12). Raw probability scores forprediction of advanced adenoma was not significantly different among 3 groups(0.55�0.06%, 0.40�0.03%, and 0.50�0.05%, respectively; pZ0.45). Conclusion:COPD, irrespective of smoking history, is an important predictor of high-risk ade-noma and may be incorporated in CRC risk calculation in African American dominantpatient population. Using previously validated CRC risk calculators (QCancer) andadvanced adenoma prediction probability models in patients where age and genderwere removed as factors, we were not able to correctly predict patients withadvanced adenoma from control patients. Our study demonstrates the diversity anddifferent weight of risk factors in African American dominant patient population incomparison with other patient populations.


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ID: 3521113HIGH CONFIDENCE OPTICAL DIAGNOSIS OF SMALLPOLYPS AT COLONOSCOPY VERSUSHISTOPATHOLOGY: MOVING TOWARDS A NEW GOLDSTANDARD?Ahmir Ahmad*, Ana Wilson, Morgan Moorghen, Angad S. Dhillon,Siwan Thomas-Gibson, Noriko Suzuki, Adam Humphries, Adam Haycock,Kevin J. Monahan, Margaret Vance, Brian P. SaundersIntroduction: Histopathology is regarded as the gold standard for diagnosis of smallcolonic polyps. However, there is growing interest in optical diagnosis and imple-mentation of a ‘resect and discard’ strategy. Our aim is to evaluate accuracy of his-topathology reporting where a high confidence diminutive polyp optical diagnosiswas made and to assess the impact of performing additional tissue section re-cuts,where there is a discrepancy. Methods: Eight bowel cancer screening colonoscopistsoptically diagnosed 639 diminutive polyps during the period Feb-Nov 2020 in theearly phase of a prospective feasibility study of optical diagnosis (DISCARD3). Eachpolyp diagnosis was evaluated by the colonoscopist as high or low confidence. Allretrieved polyps were sent for histopathology. Discrepancy between high confi-dence optical diagnoses and histopathology were re-reported by a second pathol-ogist blinded to the original optical and histological call. If discrepancy remainedafter re-review, the polyp was re-cut into deeper levels and a third blinded histo-pathology review performed (see Figure 1). Results: Of 639 diminutive polyps, 468(73.2%) were high confidence optical calls and 171 (26.8%) were low confidence.High confidence optical diagnosis agreed with histopathology in 78.2% (366/468) ofcases and disagreed in 21.8% (102/468). In cases of disagreement, the initial histo-pathology was reviewed and 7.8% (8/102) were due to histopathology error of which3.9% (4/102) corrected on second review and 3.9% (4/102) corrected with deeperlevels. There were no polyp cancers and 1 case of high-grade dysplasia. Conclusions:Although the majority of errors in optical diagnosis were related to incorrect highconfidence calls a significant number were due to histopathology error. Change inpractice to routinely perform additional deeper levels (ie 6 levels instead of 3) forsmall polyps appears to reduce this error rate by w50%. Optical diagnosis errorsmay be reduced by increasing the threshold for assignment of high confidence.

Figure 1. Overview of study


ID: 3527109ENDOSCOPIC MANAGEMENT OF COLORECTAL POLYPSIN CHALLENGING LOCATIONSFnu Chesta*, Meher Oberoi, Prabh G. Singh, Anmol Singh,Ganeev Bhangoo, Kevin T. Behm, Louis M. Wong Kee Song,Navtej S. Buttar

Background and Aim: Polyps located at certain locations are difficult to resect andare usually referred to surgery due to concern for incomplete resection or adverseevents. However, surgery is associated with significant risks. Our study aimed toassess the efficacy and safety of endoscopic resection of colorectal polyps inchallenging locations. Methods: A retrospective single-centre review of the elec-tronic medical records of all patients who underwent polyp resection by twoexperienced endoscopists from 01/2011 to 12/2019 was undertaken. Patients whounderwent surveillance colonoscopies elsewhere or in whom follow-up duration was<3 months were excluded. Data was abstracted for patient demographics, lesionlocation and morphology, resection techniques, adverse events, recurrent/residuallesions, and need for surgery. Results: A total of 244 patients (mean age 67 years; 169male) with 290 polyps in difficult locations were identified. The mean polyp size was20.8 mm (range: 2-90 mm) and 54% of the polyps were �20 mm in size. The lesionswere described as sessile (56%) and flat (35%) in most cases. The more commondifficult polyp locations were the hepatic flexure (46%), ileocecal valve (24%) andappendiceal region (13%). The majority of the lesions (271/290; 93.1%) wereremoved by snare with/without submucosal fluid lift. Adjuvant therapy to snareresection was used in 37.9% of the lesions, including argon plasma coagulation, coldbiopsy avulsion, endoloop and hot biopsy avulsion. Prophylactic clip closure wasperformed in 155/290 (53%) of the resection defects (average 5 clips/defect) andendoscopic suturing was performed in 5/290 (1.7%) of the defects. Immediate in-traprocedural bleeding and perforation occurred in 2 patients (managed by clipplacement) and 2 patients (managed by clip placement), respectively. Adverseevents occurred in 25 patients (10.2%) within 30 days of polyp removal (15 delayedbleeding, 4 perforation and 6 transmural burn syndrome); 8/25 patients requiredhospitalization. Residual/recurrent adenoma/polyp was present in 25/290 (8.6%)post resection sites: 6 cases underwent surgery and the remaining 19 were managedendoscopically. Conclusion: In experienced hands, colorectal polyps in difficult lo-cations can be managed effectively and safely with endoscopic resection.


ID: 3525882THERMAL ABLATION OF POST-EMR-DEFECTS REDUCESADENOMA RECURRENCE AFTER ENDOSCOPICMUCOSAL RESECTION OF COLONIC POLYPS: ASYSTEMATIC REVIEW AND METAANALYSISPujan Kandel*, Mohamed Abusalih, Deepesh Yadav, Murtaza Hussain,Santosh K. Dhungana, Thair Dawood, Massimo Raimondo,Ghassan Bachuwa, Michael B. WallaceIntroduction: Polypectomy during colonoscopy reduces colon cancer by 50%. Endo-scopic mucosal resection (EMR) is a standard technique for removal of large(>20mm) colorectal polyps. Adenoma recurrence is one of the key limitations ofEMR which occur in 15% to 30% in first surveillance colonoscopy. The main hy-pothesis behind adenoma recurrence is due to left over micro-adenomas at themargins of post EMR defects. In this systematic review and meta-analysis, we eval-uate the efficacy of snare tip soft coagulation (STSC) at the margins of mucosaldefects to reduce adenoma recurrence and bleeding complications. Methods:Electronic databases such as PubMed and the Cochrane library were used for sys-tematic literature search. Studies with polyps only resected by EMR, and activetreatment: with STSC, comparator: non STSC were included. Random effects modelwas used to calculate the summary of odds ratio (ORs) and 95% Confidence Inter-vals. The main outcome of the study was to compare the effect of STSC versus non-STSC with respect to adenoma recurrence at first surveillance colonoscopy afterthermal ablation of post-EMR defects and post procedural bleeding. Results: Totalthree studies were included in systematic review and meta-analysis. Total numberpatients who completed first surveillance in STSC group was 308 and non-STSCgroup was 294. Majority of polyps were resected from proximal colon compared todistal colon in both groups. There were no significant differences between treatmentand comparator group in terms of mean age and polyp size. Adenoma recurrencewas observed in 24 of 308 cases (8%) with STSC and 75 of 294 cases (25%) withoutSTSC (OR, 0.25, 95% CI: 0.15-0.41, PZ0.001), Fig 1. Post procedural bleeding wasobserved in 67/343 (19%) with STSC and 78/341 (22%) without STSC (OR, 0.74, 95%CI: 0.43-1.29) Fig 2. There was no significant heterogenicity among the trials (IsquareZ 0%, pZ0.4) and (I squareZ 0%, pZ0.41%). Conclusion: Thermal ablationof post EMR defects significantly reduces adenoma recurrence at first surveillancecolonoscopy.


Abstracts



ID: 3519884IMPLEMENTATION OF A "DAY OF SYMPTOMSSIGMOIDOSCOPY (DOSS)" PROGRAM RESULTS INEARLIER STAGE DIAGNOSIS OF LEFT-SIDED COLONAND RECTAL CANCERMatthew Fasullo*, Sarmed Al Yassin, Hamzeh Saraireh, Simran Singh,Pritesh R. Mutha, Tilak ShahIntroduction: Colonoscopy as the initial test for rectal bleeding could delay diagnosisof rectal and left sided colon cancer, since colonoscopy generally requires sedationand bowel preparation. In 2014, our tertiary veterans hospital instituted a protocolwherein primary care, emergency room, and other providers were instructed todirect patients with rectal bleeding to the endoscopy unit for unsedated sigmoid-oscopy on the same day that they reported symptoms. The aim of our study was todetermine whether this day of symptoms sigmoidoscopy (DOSS) programdecreased time to diagnosis of rectal and left-sided colon cancer, and resulted in anearlier stage at initial diagnosis. Methods: We identified patients diagnosed with leftsided (i.e. – distal to the splenic flexure) colorectal cancer (CRC) between 2005 to2019 from our institutional cancer registry. We excluded patients with only rightsided colon cancer, and asymptomatic patients in whom cancer was detected onroutine screening or surveillance examinations. We included as cases (“DOSSgroup”) left sided CRC diagnosed on sigmoidoscopy from 2014 to 2019. Controlswere left sided CRC patients diagnosed between 2005 and 2013 with eithersigmoidoscopy or colonoscopy (“Pre-DOSS group”). Controls were propensity scorematched 2:1 based on age, gender, reason for endoscopic assessment, and ASAclassification. The primary outcomes compared between cases and controls were (a)incidence of advanced (i.e. - stage 3 and 4) CRC at diagnosis (b) days between onsetof symptoms and CRC diagnosis. Results: 90 patients were included (30 cases and 60controls) (Figure 1a). As expected, due to propensity matching baseline demo-graphics were similar between the two groups (Figure 1a). Advanced (stage 3 and 4)CRC was lower in the DOSS compared to pre-DOSS group (13% vs. 30%, p 0.07).Early stage diagnosis (stage 1) was significantly higher in the DOSS compared to pre-DOSS group (63% vs 33%, p < 0.01). Days between onset of symptoms to CRCdiagnosis was significantly lower in the DOSS compared to pre-DOSS group (15 vs.77 days, p <0.01) (Figure 2). 1-year and 3-year mortality were similar between thetwo groups. Discussion: A DOSS program resulted in a sooner left-sided CRCdiagnosis after symptom onset, and earlier stage of left-sided CRC at diagnosis. Sucha protocol should be considered in settings where barriers exist towards rapid accessto colonoscopy. Larger multi-center prospective studies are necessary to confirmthat our results can generalize to other settings.

FIGURE 1. METHODOLOGY AND DEMOGRAPHICS

FIGURE 2. PRIMARY AND SECONDARY OUTCOMES


Abstracts



ID: 3515704HIGH PREVALENCE OF DYSPLASIA IN PROXIMALSESSILE SERRATED LESIONSYi Yuan Tan*, Sei Kiat Tay, Yu Jun Wong, James Weiquan Li,Boon Eu Kwek, Tiing Leong Ang, Lai Mun Wang, Malcolm TanBackground and Aim: Proximal colorectal cancers (CRCs) account for up to half ofinterval CRCs. Sessile serrated lesions (SSLs) are precursors to CRC. Proximal sessileserrated lesions (pSSLs) are associated with higher risks of dysplasia and progressionto proximal CRC, the prevalence of dysplasia and characteristics predictive ofdysplasia among proximal SSLs (pSSLs) are not well studied.We aimed to determinethe prevalence and predictors of dysplasia among pSSLs. Methods: In this retro-spective, observational study conducted in a tertiary referral hospital, we systemat-ically reviewed all endoscopically resected colonic polyps at our centre betweenJanuary 2016 and December 2017. Clinical and endoscopic data of patients with atleast one pSSL were retrieved from electronic medical records. We compared theclinic-pathological features of pSSLs with and without histological evidence ofdysplasia. Results: Among 637 patients were reviewed (mean age 63 years, 52.2%were male), we identified 90 pSSLs. The median size of pSSLs was 4mm (IQR: 3-6mm), of which 13.3% were �10mm. pSSLs were most commonly detected in theascending colon (51.1%) followed by cecum (26.7%) and transverse colon (22.2%).The prevalence of dysplasia among pSSLs was 50.0% (45/90). Among pSSLs withdysplasia, 60% had polyp size<5mm. Factors that were significantly associated withthe presence of dysplasia among pSSLs were older age (65.9 vs 60.1 years, pZ0.034)and polyp size �10mm (83% vs 45%, pZ0.013). Synchronous SSLs, smoking historyand family of CRC were not predictive of dysplasia among pSSLs. After adjusting forage, pSSLs �10mm is predictive of dysplasia among pSSLs [OR: 5.98 (95% CI: 1.21 –

29.6)]. Conclusions: Our study highlights a high prevalence of dysplasia amongpSSLs, with polyp size �10mm being predictive of dysplasia among pSSLs. Asdysplasia can still occur in a significant proportion of diminutive polyps (<5mm), en-bloc endoscopic resection for all pSSLs is crucial to facilitate accurate histopatho-logical examination for dysplasia, the presence of which warrants shorter surveil-lance interval.


ID: 3527212A RETROSPECTIVE COHORT STUDY OF PATIENTS WITHPOSITIVE COLOGUARD RESULTS AT A RURAL TERTIARYCOMMUNITY HOSPITALJane E. Lindsay*, Stewart Hargrove, Chuan Long MiaoIntroduction: Since receiving FDA approval in 2014, the use of multitarget stool DNAtesting (MT-sDNA or Cologuard) testing has become a reputable option for colo-rectal cancer (CRC) screening amongst appropriate patient populations. The highsensitivity provided by Cologuard promises providers a powerful screening tool forcolorectal cancer. The original study evaluating the statistical parameters of Colo-guard, should represent a general patient population. However, given the controllednature of clinical trials, further evaluation in real-life clinical practice was needed.Aim: To confirm the potential colonoscopy findings listed by Exact Science onpositive Cologuard test results in real-life clinical setting. Methods: In this study, dataof all patients referred to our gastroenterology clinic with a positive Cologuard testwere retrospectively collected. Patients were selected from a 34 month time window(1/1/2018-9/30/2020). Clinical parameters such as age, nicotine use and wait time(Table 1, 2) were collected. We defined wait-time as the period between the time aCologuard test was ordered to the time a follow up colonoscopy was performed.Results: In total 54 patients were referred to our clinic with a positive Cologuard testresult during the 34 month time period. Twelve patients were excluded owing to nothaving completed a colonoscopy. One of the remaining 42 patients in fact had anegative Cologuard result. Leaving a total of 41 patients for analysis.Within this cohort, two patients were found to have CRC, 13 were found to have anadvanced 4adenoma, 15 had a non-advanced adenoma and 11 had negative findings(table 3, 4). Regarding prior screening history, only 17 patients total had previouslyundergone screening. Of the remaining 24 previously unscreened patients, one wasfound to have a CRC and 11 were found to have advanced adenomas.Though the wait-time was mostly under 5 months, delays were found up to 17months. Both of the patients found to have CRC had extensive delays (Table 5).Discussion: In addition to essentially matching the statistical data listed by Exact Sci-ence our study found several secondary observations. Cologuard is being utilized onpatients who have previously avoided screening colonoscopy. And unlike ascreening colonoscopy, the Cologuard is plagued with delays at multiple stages.Conclusions: With the exception of detecting more non-advanced adenomas, our

study essentially confirmed the data promised by Exact Science. Though it seemsto be vulnerable to delay- which does appear to be more prominent in the COVID 19pandemic era- a positive Cologuard test can convince a reluctant patient to undergoa life-saving colonoscopy.


ID: 3524643RISK FACTORS FOR HIGH-RISK COLORECTALADENOMA AT THE FOLLOW-UP COLONOSOPY INPATIENTS WITH REMOVED HIGH-RISK ADENOMA/EARLY COLORECTAL CANCER: A PROSPECTIVECOHORT STUDYEun Ji Lee, Hyuk Yoon, Min Kyu Kim, Cheol Min Shin, Young Soo Park,Nayoung Kim, Dong Ho Lee*Background/Aim: To evaluate the risk for high-risk colorectal adenoma/neoplasm(HRCAN; 3 or more adenomas, adenoma � 1cm, adenoma with high-degreedysplasia and/or villous component, or in situ cancer), in patients who underwentendoscopic resection for high-risk colorectal polyp (HRCP; 3 or more polyps,adenoma or serrated lesion � 1cm, adenoma with high-degree dysplasia and/orvillous component, or in situ cancer). Methods: Patients undergoing endoscopicresection for HRCP were prospectively enrolled and they were recommendedfollow-up colonoscopy one year later. The primary outcome was development ofHRCAN in the first follow up colonoscopy. Multivariate logistic regression was per-formed to evaluate the risk factors for HRCAN. Results: In total, 378 adults withHRCP removed by colonoscopy were enrolled in the cohort. 228 patients (60.3%)underwent follow up colonoscopy and the median follow up interval was 371.5 days.Among 228 patients, 35 had HRCAN at the first follow up colonoscopy; 28 had 3 ormore adenomas, 4 had adenoma � 1cm, 6 had adenoma with villous components,and 1 submucosal cancer. We calculated the odd ratio (OR) for each variable andonly hypertension (HTN) was a statistically significant; HRCAN occurred in 17 of 34patients (50%) in patients with HTN and 18 of 194 (9.3%) in patients without HTN,with an OR of 2.08 [95% confidence interval, 1.00 to 4.31]. The presence of HRCANor HRSL at the first colonoscopy did not significantly affect the occurrence ofHRCAN at the first follow up colonoscopy. Besides 35 cases of HRCAN, we found 7high risk serrated lesions (HRSL; sessile serrated adenoma or hyperplastic � 1cm,any traditional serrated adenoma, 3 or more serrated polyp). Conclusion: HTN is arisk factor for developing HRCAN at the 1-year follow-up colonoscopy. Furthermore,given that high-risk adenomas and serrated lesions were found in 18.4% of patients,


Abstracts


1-year follow-up colonoscopy is thought to be meaningful in patients with removedhigh-risk adenoma/early colorectal cancer, especially those with hypertension.


ID: 3522572COLD SNARE POLYPECTOMY VERSUS COLD FORCEPSPOLYPECTOMY FOR DIMINUTIVE AND SMALLCOLORECTAL POLYPS: A SYSTEMIC REVIEW AND META-ANALYSIS OF RANDOMIZED CONTROLLED STUDIESJustin Chuang*, Azizullah Beran, Sami Ghazaleh, Yasir Alabboodi,Mohammed Mhanna, Omar Srour, Hazem Ayesh, Ali NawrasIntroduction: Diminutive (1-5mm) and small (6-9 mm) colorectal polyps arefrequently found during screening colonoscopy. Cold snare (CSP) and cold for-ceps (CFP) are commonly used techniques for the removal of diminutive and smallpolyps. However, the optimal technique as regards effectiveness and safety remainsuncertain. Therefore, we conducted a systematic review and meta-analysis of allrandomized controlled studies that compared the effectiveness and safety of CSPversus CFP in diminutive and small colorectal polyps. Methods: We performed acomprehensive literature search using the MEDLINE and EMBASE databases frominception through November 2020. Only randomized controlled studies (RCTs) thatcompared CSP versus CFP were included. The primary outcome of interest was theincomplete resection rate (IRR). Secondary outcomes were procedure time, failureof tissue retrieval, post-polypectomy bleeding, and perforation rates. All meta-ana-lyses were conducted using a random-effect model. Pooled rates were reported asrisk ratios (RR) or mean difference (MD) with 95% Confidence Interval (CI). Het-erogeneity was assessed using the Higgins I2 index. Results: Eight RCTs, including atotal of 958 patients with 1168 polyps (554 in CSP and 614 in CFP) met our inclusioncriteria and were included in the final analysis. The IRR was significantly lower in CSPgroup compared to CFP group: 6% vs. 11.9%; RR -0.06, 95% CI [-0.10, -0.02], P Z0.003, I2 Z 35% (Figure 1). Failure of tissue retrieval rate was significantly higher inCSP group compared to CFP (RR 9.60; 95% CI [2.20, 41.77], P Z 0.003, I2 Z 0%)(Figure 2). Only two studies reported procedure time which was significantly shorterin CSP group compared to CFP group MD -5.87, 95% CI [-10.86, -0.88], P Z 0.02, I2Z 47% (Figure 2). There were no adverse events found in both groups includingperforation, and post-polypectomy bleeding. Conclusions: Compared to CFP, CSPshowed a lower incomplete resection rate and shorter procedure time. However,CSP had a higher failure of tissue retrieval rate. Further studies with a larger samplesize are warranted to confirm our results.

SATURDAY, MAY 22, 2021Colon and Rectum 1Lecture

ID: 3523373NON-CURATIVE ENDOSCOPIC SUBMUCOSALDISSECTION (ESD) FOR COLORECTAL CANCER:CLINICAL OUTCOMES AND PREDICTORS OFRECURRENCEMarco Spadaccini*, Michael J. Bourke, Roberta Maselli, Mathieu Pioche,Pradeep Bhandari, Jeremie Jacques, Amyn Haji, Dennis Yang,Eduardo Albeniz, Michal F. Kaminski, Helmut Messmann,Alberto Herreros De Tejada, Sandro Sferrazza, Boris Pekárek,Jerome Rivory, Sophie Geyl, Shraddha Gulati, Peter V. Draganov,Neal C. Shahidi, Hossain Ejaz, Carola Fleischmann, Edoardo Vespa,andrea iannone, Asma A. Alkandari, Cesare Hassan, Alessandro RepiciBackground and Aim: Endoscopic submucosal dissection (ESD) is an organ-preser-ving approach pursuing curative intent for the removal of superficially invasivecolorectal cancers (CRCs) with negligible risk for lymph-node metastasis.Conversely, additional surgical resection is recommended in case of high risk ofnodal involvement based on histo-pathological features. However, both the actualrisk of a lymph-node disease and the clinical outcomes of patients who underwentnon-curative ESD has never been investigated. The aim of this study is to reportoutcomes of these patients from a large Western cohort. Methods: This was aretrospective analysis of consecutive patients with CRC who underwent ESD at 13tertiary-care centers. All lesions with histo-pathologic features of high risk of nodalinvolvement were considered for the analysis, regardless of post-endoscopic man-agement (Conservative vs Surgery). Primaryoutcomes were disease recurrence,death and disease-related death rates after non-curative ESD in the two groups. Assecondary outcomes, we assessed the rate of residual disease (RD) at both theprevious resection site and regional lymph-nodes among patients who underwentsurgery. Endoscopic and histologic variables were investigated as risk factors for RD.Results: From October 2012 to November 2019, 3373 patients have been treated bycolorectal ESD and 207 non-curative resections were considered for the analysis.The 60.9%(nZ126) of these patients were referred for surgery, and the remaining39.1%(nZ81) were followed up. In a mean time of 27.6�18.6 months, there was nodifference in term of recurrence rate between the two groups(pZ0.30). The Con-servative group showed a higher risk of death for any causes compared to theSurgery group(HRZ3.99, pZ0.013). Conversely no difference was reportedconsidering disease-specific survival rate. Among patients who underwent additionalsurgery, 25 patients(19.8%) had histological evidence of RD, with lymphatic-vascularinvasion (HRZ3.48, pZ0.009) and depth of invasion >sm (HRZ4.98, pZ0.017)emerged as independent predictors. Conclusions: Additional surgical resection maybe not clinically relevant in all cases of non-curative ESD. Lymphatic-vascular inva-sion and/or the neoplastic involvement of the muscular layer should strongly suggesta surgical approach.


ID: 3526954FOUR-YEAR PROGNOSIS SURVEY AFTER COLORECTALESD -MULTICENTER PROSPECTIVE STUDY AMONGJAPANESE FOREFRONT-Keita Harada*, Nozomu Kobayashi, Ken Ohata, Yoji Takeuchi,Akiko Chino, Masayoshi Yamada, Yosuke Tsuji, Kinichi Hotta,Hiroaki Ikematsu, Toshio Uraoka, Takashi Murakami, Hisashi Doyama,Takashi Abe, Atsushi Katagiri, Shinichiro Hori, Tomoki Michida,Takuto Suzuki, Masakatsu Fukuzawa, Shinsuke Kiriyama,Kazutoshi Fukase, Yoshitaka Murakami, Hideki Ishikawa, Yutaka SaitoBackgrounds and Aims: Colorectal endoscopic submucosal dissection (C-ESD) hasbeen developed by Japanese expert colonoscopists, which is one of the mosteffective treatments for early-stage cancer due to its high en-bloc resection rate andhigh accuracy of histopathological evaluation. There were, however, few reportswhich systematically investigated the treatment results, especially long-term recur-rence rates so far. The aims of this study were to clarify the prognostic outcomes ofC-ESD though a large-scale multicenter prospective study. Materials and Methods:From February 2013 to January 2015, 1,883 patients were enrolled in this study from20 institutions all over Japan and C-ESD was performed on a total of 1,965 lesions.Among them, 1,577 lesions of 1,493 patients who underwent follow up colonoscopyat least once within four years after C-ESD were analyzed. Results: The median age attreatment was 69 y-o (31-89). The average tumor size of the resected specimen was34.5�16.4 mm. 1,214 of 1,305 lesions which were removed in complete en-blocfashion by means of ESD were finally diagnosed as pathologically curative. Out of


Abstracts


remaining 363 lesions, 107 underwent additional surgery due to non-curativeresection. 1,000 patients have underwent twice or more surveillance colonoscopiesfor over two years after C-ESD. Local recurrence has occurred only in five lesions indifferent patients (0.4% of 1,198 lesions without additional surgery). Among them,four were found early within 16 months at the site after R1 resections of intramu-cosal cancer. The other one recurred in the scar of T1a (submucosal slight invasion)cancer which has been considered as curative resection and was first found during asecond surveillance performed in the third year after ESD. All five cases were re-treated endoscopically, and all resected specimen were adenomas, resulting incomplete cure. Meanwhile, metachronous colorectal neoplasia was found in 33/1,493 (2.2%) patients within three years after C-ESD. Among those 33 lesions, 15were invasive cancers and 13 required surgical operation as a retreatment. There wasa statistically difference in the occurrence of metachronous colorectal neoplasiabetween patients who had harbored single C-ESD lesion and those who had beenwith multiple C-ESD lesions (1.7% vs. 8.3%, p Z 0.001), although there was nodifference according to the curability of C-ESD lesion(s). Discussion: C-ESD had ahigh curative resection rate and the risk of local recurrence within at least four yearswas extremely low. On the other hand, the risk of occurrence of metachronouscolorectal neoplasia within four years tended to be high, especially in patients whohad underwent C-ESD for multiple lesions. Conclusions: Surveillance colonoscopywithin four years after C-ESD should be paid attention to metachronous colorectalneoplasia rather than local recurrences.


ID: 3526950USE OF A DOUBLE BALLOON PLATFORM FACILITATESENDOSCOPIC SUBMUCOSAL DISSECTION (ESD) OFCOMPLEX COLON LESIONS AND DECREASES POST ESDLENGTH OF STAY(LOS): A SINGLE CENTER CASEMATCHED STUDYStavros N. Stavropoulos*, Nasim Parsa, Jessica L. Widmer,Maaz B. Badshah, Tarek H. Alansari, Dmitriy O. Khodorskiy,Rani J. ModayilBackground: ESD in the colon is challenging. A new double balloon (DB) platform(DiLumen, Lumendi, Westport, CT) is proposed to facilitate colon ESD by improvedendoscope stability. It may accelerate safer patient discharge by enabling routinesuturing of the ESD defect. It allows rapid, easy insertion of the endoscopic suturingdevice (Overstitch, Apollo Endosurgery, Austin, TX) via the balloon-anchored sheathof the DB platform, which can otherwise be challenging to advance beyond thesigmoid, so typically less secure endoclips are used for closure. We aim to assesspotential benefits of DB-assisted ESD (DBA-ESD) compared to conventional ESD (C-ESD) for complex colon lesions. Methods: From 1/18 to 3/20, 130 colon lesions hadDBA-ESD. Initial 50 cases were excluded to mitigate DBA-ESD learning curve bias.Subsequent 80 were matched to 80 C-ESDs performed prior to the DBA-ESD period(2016-2017, after the operator’s first 300 ESDs, avoiding learning curve bias for C-ESD). Propensity score matching was used for age, gender, lesion area (cm2),difficult location, and prior lesion manipulation (tattoo, argon plasma, EMR)/fibrosis.Procedure time and dissection speed were compared to assess how DB facilitatedESD. Analysis comparing 45 DBA-ESDs with suturing of the defect vs 45 propensity-score matched C-ESDs with endo-clip closure was performed to determine if su-turing of the ESD defect minimizes admission rates. The lower number for thisanalysis is because routine suturing of the ESD defect was only done later in ourDBA-ESD experience, after developing a method to insert the gastroscope lengthsuturing device through the colonoscope-length DB sheath. Results: There was nodifference between the 80 C-ESDs and 80 DBA-ESDs baseline characteristics (Table1). There were no severe AEs that required surgery, IR, other interventions, orprolonged hospitalization. Median dissection speed was significantly faster and totalESD time significantly shorter in the DBA-ESD group. [Table 1]. In the analysis of 45matched C-ESD patients with endo-clip closure vs. 45 D BA-ESD patients with su-tured closure there were no significant differences in baseline characteristics. TheLOS was significantly shorter in the DBA-ESD group with a higher same daydischarge rate [Table 2]. Conclusion: We performed a case-control study of DBA-ESD vs C-ESD for colon lesions using propensity score matching of cases and con-trols from a large prospective US single center cohort with a high volume of chal-lenging lesions including w50% with prior manipulation and difficult location. TheDB platform, by offering endoscope stabilization and easy insertion of the endo-scopic suturing device for secure ESD defect closure increased colon ESD speed,reduced overall ESD time, decreased LOS and increased the same-day dischargerate. Further studies are needed to confirm these promising results.

Table 1

Table 2


ID: 3527049ENDOSCOPIC MUCOSAL RESECTION (EMR) VERSUSENDOSCOPIC SUBMUCOSAL DISSECTION (ESD) FORFLAT COLORECTAL POLYPS GREATER THAN OR EQUALTO 20MM: COST CONSEQUENCE MODELStavros N. Stavropoulos*, John Hauschild, rituparna basu,Jessica L. Widmer, Rani J. ModayilBackground: EMR has been shown to be less morbid and more cost-effective relativeto surgery for flat colon polyps greath than 2cm. Shortcomings include inability toresect poorly lifting lesions and piecemeal resection which results in higher recur-rence rates and poor histologic margin assessment. ESD offers reliable en bloc,margin negative resection (R0) with associated lower recurrence rates (and thuspresumably lower rates of surveillance colonoscopies and treatment of recurrences).On the negative side, from a cost perspective, colon ESD may have higher compli-cations and procedural costs and a long learning curve. In the absence of random-ized data, cost comparisons are dependent on modeling. Some prior attempts havefavored EMR but only focused on the initial procedure without factoring in the needfor surveillance colonoscopies. With the rising number of colon ESD centers ofexcellence in the US, it would be topical to analyze the overall treatment episodes.The aim of our study was to compare the cost consequences of EMR vs. ESD for ahypothetical cohort of patients with flat colon lesions >20mm. Methods: Costconsequence model from a provider perspective using TreeAge Pro software. Actualcost information for procedures, intra-operative and post-operative complications,was obtained from 2017 healthcare data sourced from the Premier Database, whilethe probability of an outcome was obtained from published literature. Since CPTcodes do not exist for ESD, proxy procedure costs were assigned based on timeparameters. Piecemeal EMRs were defined as EMR procedures � 45 and <90 mi-nutes, while ESD procedures were defined as resection procedures >90 minutes.Recurrences detected on colonoscopy plus biopsy (CBx) were followed by colo-noscopy with salvage treatment(s), sensitiviy analysis with variant scenarios was also


Abstracts


performed. Results: Costs and event probabilities appear in table I and decision treein fig. 1. Weighted costs: EMR $2,268, ESD $4,145, CBx $1,473, colectomy $13,492.After 100 Piecemeal EMR and ESD procedures were run through the initial pro-cedure and surveillance model the overall cost per EMR patient was $7,840compared with $7,040 for ESD. One hundred patients run through the ESD plussurveillance treatment arm results in 8 less surgeries, 21 less further endoscopicresections, and 79 less surveillance colonoscopies than EMR plus surveillance. Analternate scenario where EMR for a recurrence is performed at the same session asthe surveillance colonoscopy saves approximately 24 surveillance colonoscopies andresults in a lower EMR cost of $7,480) reducing the per treatment episode costsavings of ESD to $440. Conclusion: ESD has the potential to reduce costs and moreimportantly patient burden by not only reducing the number of surgeries, but alsothe number of coloscopies for surveillance and salvage resections of recurrences.

Table 1

Decision Tree


ID: 3520676PREDICTIVE FACTORS FOR INTERRUPTION,PIECEMEAL RESECTION, AND PERFORATION AFTERSTANDARDIZATION OF COLORECTAL ENDOSCOPICSUBMUCOSAL DISSECTIONYuki Kamigaichi*, Shiro Oka, Shinji Nagata, Masaki Kunihiro,Toshio Kuwai, Yuko Hiraga, Akira Furudoi, Seiji Onogawa,Hideharu Okanobu, Takeshi Mizumoto, Tomohiro Miwata,Shiro Okamoto, Hidenori Tanaka, Ken Yamashita, Yuki Ninomiya,Shinji TanakaBackground and Aim: Colorectal endoscopic submucosal dissection (ESD) has beenstandardized in Japan; however, interruption, piecemeal resection, and perforationare persistent problems. This study aimed to evaluate the predictive factors forabove problems after standardization of colorectal ESD. Patients and Methods: Thismulti-center prospective observational study from the Hiroshima GastrointestinalEndoscopy Research Group (11 institutions; Hiroshima University Hospital and 10affiliated hospitals) included a total of 2,423 consecutive patients (1,453 men, meanage: 69�10 years) who underwent ESD for 2,592 colorectal tumors between August2013 and December 2018. We evaluated the predictive factors for interruption,piecemeal resection, and perforation in relation to clinicopathological and endo-scopic features (tumor size, location, situation, growth type, pathological diagnosis,depth of invasion, bleeding during the procedure, degree of submucosal fibrosis,history of biopsy, history of local endoscopic treatment, history of abdominal sur-geries, operator experience, the retrograde approach, time of the procedure, andscope operability). We also evaluated the predictive factors for severe submucosalfibrosis using preoperatively assessable variables without a history of local endo-scopic treatment. Results: ESD was performed by a total of 49 endoscopists (9 ex-perts and 40 non-experts). The mean size of tumors was 30�14 mm, and the meanprocedure time was 84�68 min. En bloc resection rate was 96.4% (2,499/2,592), andthe incidences of interruption, piecemeal resection, and perforation were 0.7% (18/2,592), 2.9% (75/2,592), and 3.0% (78/2,592; 73 perforations during procedure and 5delayed perforations), respectively. Emergency surgery was required in 16.4% (12/78) of perforation cases. Multivariate analysis identified followings; 1) the predictivefactors for interruption: occurrence of perforation during procedure, deep submu-cosal invasion (>1,000 mm), poor scope operability, and severe submucosal fibrosis,2) the predictive factors for piecemeal resection: poor scope operability, severesubmucosal fibrosis, and long procedure time (�85 min), 3) the predictive factorsfor perforation during procedure: severe submucosal fibrosis, poor scope opera-bility, long procedure time (�85 min), and tumor size (�40 mm). Severe submu-cosal fibrosis was identified as a common predictive factor for interruption,piecemeal resection, and perforation, and it was observed in 18.7% (230/1,228) ofthe lesions on the fold or flexure. Conclusion: Severe submucosal fibrosis and poorscope operability are the common predictive factor for interruption, piecemealresection, and perforation after standardization of colorectal ESD. Prediction of se-vere submucosal fibrosis prior to ESD was difficult.


ID: 3521919IMPACT OF GROSS TUMOR MORPHOLOGY ON THECLINICAL OUTCOMES OF NON-METASTATIC COLONCANCER : MULTICENTER RETROSPECTIVE COHORTSTUDYSo Jung Han*, Bun Kim, Dae Bum Kim, Jae Hyun Kim, Il Hyun Baek,Jun Lee, Byung Ik Jang, Hyun Gun Kim, Hyun Seok Lee, Jae Jun ParkBackground/Aims: There has been no data regarding the association between grossmorphology and clinical outcomes of colon cancers. We aimed to investigate therelationship between endoscopic features and outcomes of non-metastatic coloncancer. Methods: The study is a retrospective analysis based on the colon cancercohort data of the colon cancer study group in the Korean Society of GastrointestinalCancer. Patients were followed-up and treated for colon cancer from 2010 through2019. Data for clinical characteristics and treatment outcomes were retrieved. Allpatients received curative endoscopic or surgical resection as initial therapy. Coloncancer gross morphology was categorized into two groups, including flat/ulceroin-filtrative type or fungating/ulcerofungating type based on endoscopic images. Stag-ing of colon cancer followed AJCC 7th guideline. In multivariate Cox regressionanalysis, the following variables, including age, gender, family history of colon can-cer, Carcinoembryonic antigen at diagnosis, diabetes mellitus, staging, tumor loca-tion and gross tumor morphology was included. Results: A total of 1205 patients


Abstracts


(mean age 64�12 years, male 60.1%) were included. Regarding gross tumormorphology, 343 (28.5%) patients showed flat/ulceroinfiltrative type; meanwhile 862(71.5%) patients showed fungating/ulcerofungating type. Flat/ulceroinfiltrative typecancer showed a significantly shorter time to recurrence (PZ0.002) and shortersurvival (PZ0.002) compared with fungating/ulcerofungating type cancer, and it wasconsistent in rectal cancer subgroup. In the subgroup analysis by stage, survivaldifference concerning gross tumor morphology was more prominent in stage IIpatients group. In multivariate Cox regression, gross tumor morphology (hazardratio 1.525, confidence interval 1.059 2.198) was independent prognostic factors forsurvival. Conclusion: Our data indicate that gross tumor morphology with flat/ul-ceroinfiltrative type is independent prognostic factors for poor survival in non-metastatic colon cancer. This prognostic difference was more prominent in stage IIcolon cancer patients.

Table 1. Baseline Characteristics{CEA : Carcinoembryonic antigen ; yNeoadjuvant or Adjuvant therapy(chemotherapy or radiotherapy)

Table 2. Multivariate Cox regression


ID: 3520791COLONOSCOPY RESULTS AFTER A POSITIVE STOOLDNA TEST: EXPERIENCE FROM A COMMUNITYSCREENING POPULATIONSaumya Patel*, Sarah Grace Bowyer, Joseph J. Vicari, Aaron Shiels,Brad Bowyer, Chandrashekhar Thukral, Ilche T. Nonevski, Sunil Patel,Matthew W. StierIntroduction: Colonoscopy remains the gold standard screening test for colorectalcancer. Recently there has been increased use of mt-sDNA testing, a Tier 2screening test, in the community setting. Few studies have evaluated the perfor-mance of mt-sDNA in clinical practice. This study evaluates colonoscopy findings inpatients presenting after a positive mt-sDNA test in relation to a screening popula-tion. Methods: Medical records at a high-volume community GI practice werequeried for colonoscopies from 2016-2020 with an indication of “positive mt-sDNA”and “screening colonoscopy”. Baseline patient demographics and procedural datawere extracted. Exclusion criteria included prior adenoma, family history of coloncancer, secondary indication for GI symptoms, history of IBD, inadequate bowelpreparation and incomplete procedure. Statistical analysis was performed via Chi-Square or Two-Sample t-test. Results: Mt-sDNA was ordered inappropriately for 68/440 (15%) patients: 32 with prior adenoma, 13 with secondary indications, and 23with a family history of colorectal cancer. 348 patients with a positive mt-sDNA testand 446 screening colonoscopy patients were included. mt-sDNA patients wereolder than the screening cohort (64.7 vs 59.2 years, pZ2.78E-20) and containedmore female patients (63.8% vs 54.0%). Scope withdrawal time was longer in pa-tients with a positive mt-sDNA test (15.7 vs 13.3 min, pZ9.2E-7). In the positive mt-sDNA cohort, 33.9% (118) of patients had no adenomas, 33.62% (117) non-advancedadenomas only, 30.46% (106) advanced adenomas, and 2.01% (7) colorectal cancer.When compared to the screening colonoscopy cohort, patients presenting after apositive mt-sDNA test were more likely to have an advanced adenoma (30.5% vs7.6%, pZ5.38E-17) or cancer (2.0% vs 0.22%, pZ.012), and were less likely to haveno adenomas (33.9% vs 50.5%, pZ.3.03E-06). Screening colonoscopy detectedmore non-advanced adenomas (41.7% vs 33.6%, pZ.019). Adenoma detection ratewas higher in those with a positive mt-sDNA test (66.0% vs 49.6%, pZ3.03E-6).Patients with a positive mt-sDNA test and no adenomas were more likely to havediverticulosis (46.04% vs 41.78%, pZ.028) or hemorrhoids (30.94% vs 24.44%,pZ.019). Conclusion: Two thirds (67%) of patients undergoing colonoscopy for apositive mt-sDNA test were found to have no adenomatous polyps or low-risk ad-enomas only. 2% of patients with positive mt-sDNA testing had colorectal cancer. Mt-sDNA testing was ordered inappropriately in 15% of patients referred for follow upcolonoscopy. Additional education regarding appropriate use and interpretation ofmt-sDNA testing is needed in the primary care setting.


Abstracts



ID: 3524139MONITORING COLONOSCOPY QUALITY ACROSS THESPECTRUM OF CANCER CONTROL INDICATIONS: THEADR-ESS (ADENOMA DETECTION RATE – EXTENDED TOALL SCREENING AND SURVEILLANCE) SCOREUri Ladabaum*, Ajitha MannalitharaBackground: The adenoma detection rate (ADR), strictly based on first-timescreening colonoscopies, is the best validated colonoscopy quality metric. Audit-ing other colonoscopy indications could increase sample size per endoscopist andimprove the precision of ADR estimates and their stability over time, as well asemphasize quality across the spectrum of preventive colonoscopies.Aims: To develop the aggregate ADR-ESS (ADR extended to all screening and sur-veillance) score and assess its precision and stability vs. ADR. Methods: Data wereextracted for 15,253 colonoscopies by 35 endoscopists in the Stanford ColonoscopyQuality Assurance Program for Oct,2017–Jan,2020. Two versions of ADR-ESS wereexplored: ADR-ESS1 was a simple aggregation of preventive colonoscopies (firstscreening, subsequent screening, surveillance, family history of colorectalneoplasia), and ADR-ESS2 included normalization of rates with respect to firstscreening and weighting of indications based on the proportions of an endoscopist’scolonoscopies. We compared ADR-ESS1 vs. ADR-ESS2 vs. ADR by endoscopist withrespect to width of confidence intervals (CI), endoscopist ranking, and stability overtime and colonoscopy volume. Results: Relative to first screening, adenoma detec-tion rates were lower for subsequent screening (RR 0.80, 95%CI 0.74-0.87) andfamily history (RR 0.84, 95%CI 0.74-0.96) and higher for surveillance (RR 1.22, 95%CI1.15-1.31). Colonoscopy volumes for ADR-ESS were 3.4-fold (range 2.0-7.9-fold)higher than for ADR. The quintiles for ADR were <27%, 27 to <35%, 35 to <38%, 38to <44% and �44% vs. quintiles for ADR-ESS1 of <32%, 32 to <35%, 35 to <39%, 39to <43% and �43%, and for ADR-ESS2 of <31%, 31 to <35%, 35 to <40%, 40 to<43% and �43%. The CIs for ADR-ESS1 and ADR-ESS2 were substantially narrowerthan for ADR; the numerical ranking of endoscopists by ADR-ESS1 vs. ADR-ESS2were very similar, but differed somewhat from ranking by ADR (Fig 1).Endoscopists’ ADR-ESS1 showed less variability by quarter than ADR (Fig 2).Quarter-to-quarter fluctuations in ADR-ESS1 were minimal for endoscopists with�500 total colonoscopies. Period-to-period variability decreased substantially with

semi-annual audit for ADR-ESS1, but less substantially for ADR (Fig 2). ADR-ESS1 andADR were both relatively stable year-to-year, except for endoscopists with the lowestcolonoscopy volumes. Conclusions: A simple aggregation of the four major pre-ventive colonoscopy indications into the ADR-ESS score yields a more precise andstable metric than the classic ADR based only on first time screens, without requiringchanges to detection benchmarks. Beyond increasing the colonoscopy volumeavailable for audit, ADR-ESS has the added advantage of emphasizing quality assur-ance across the range of CRC control indications.

Fig 1. ADR-ESS and ADR confidence intervals and endoscopist ranking

Fig 2. Stability of ADR-ESS vs. ADR quarter-to-quarter and semester-to-semester


ID: 3524342IMPACT OF COVID-19 PANDEMIC ON COLORECTALCANCER SCREENING WHEN COLONOSCOPY IS THEDOMINANT SCREENING MODALITYGabrielle Waclawik*, Mark Benson, Patrick Pfau, Jennifer WeissBackground: The COVID-19 pandemic led to a temporary cessation of elective pro-cedures throughout the country and a dramatic decrease in screening colonoscop-ies. It is unknown if the COVID-19 pandemic affected all CRC screening modalitiesequally and overall screening rates. Aim: To determine CRC screening rates duringthe COVID-19 pandemic in a large unified health system where colonoscopy is thedominant screening modality. Methods: Billing and electronic medical record (EMR)data was collected to determine the number of CRC screening tests completed bymodality over 15 months (July 2019–Sept 2020). Data collection was limited to ageappropriate patients (50-75 years). CRC screening test completion was determinedby CPT codes for (a) fecal occult blood test (FIT/gFOBT), (b) multitarget stool DNA,


Abstracts


(c) flexible sigmoidoscopy, (d) CT colonography, and (e) colonoscopy. Two samplet-test was performed by modality to compare average monthly procedures for themonths pre- and post-initial COVID surge. In addition, reasons for endoscopycancellation were reviewed from the EMR for July 2020-Oct 2020. Results: In 2019,overall CRC screening rates for the unified health system were 84.5% (NZ61,410/72,248) with colonoscopy as the dominant screening choice (73%). On average fromJuly 2019-Feb 2020, 1,641 screening colonoscopies were performed per month. InMar-Apr 2020, the monthly average dropped to 481 colonoscopies, a 70% decreasecompared to pre-COVID screening [t(8)Z9.3, p<0.00001]. In May 2020, pre-pro-cedure COVID testing was instituted (nasal swab rapid test performed within 72 hrsprior to procedure) and in the following months the number of screening colo-noscopies increased to an average of 1,174 per month. This was a significant in-crease from the procedures in Mar-Apr 2020 [t(5)Z2.9, pZ0.034], but remainedsignificantly lower than pre-COVID screening [t(11)Z4.5, pZ0.001]. We saw asimilar drop in use of our most common non-invasive screening test (multitargetstool DNA), as well as a similar rebound after the initial COVID surge. Use of all othermodalities which were much less frequent pre-COVID remained stable (Figure 1). Atotal of 341 endoscopic procedures were canceled between July 2020-Oct 2020 evenafter pre-procedure COVID testing, 43% were due to COVID-related reasons.Conclusions: 1) The COVID-19 pandemic significantly affected CRC screening withboth invasive (colonoscopy) and non-invasive (multitarget stool DNA) tests. 2) Ina system with high overall CRC screening rates (>80%) with colonoscopy as thedominant CRC screening modality, procedure volume was able to resume at 72%pre-COVID monthly averages after institution of strict pre-procedure COVIDscreening and testing. 3) Even with an increase in colonoscopy screening after theinitial COVID surge, patient cancellation due to COVID-related reasons remainshigh.

Figure 1. CRC screening test completion by modality (July 2019-Sept2020)


ID: 3524600EFFECT OF INCORPORATING SIMETHICONE IN BOWELPREP ON POLYP AND ADENOMA DETECTION RATE INNON-CLINICAL TRIAL SETTINGRam G. Gorantla*, Subhash Chandra, Ryan W. Walters, William Reiche,Anna L. Cheek, Omar AlaberBackground: Simethicone’s antifoaming properties have potential to improvemucosal visualization during colonoscopy. Here, we evaluate effect of incorpo-rating simethicone in bowel preparation on polyp and adenoma detection rate.Methods: In July 2018, we added simethicone 100 mg 2 tablets with last cup of split-bowel prep in our academic practice. We included consecutive average risk adultsundergoing screening colonoscopy, between July 2019 to Sept 2019 as interventionarm and April 2019 through June 2018 as historical control arm. Average risk wasdefined based on lack of family history for colorectal cancer and personal history ofadenoma. Outcomes assessed were polyp detection rate (PDR), adenoma detectionrate (ADR), sessile serrated adenoma detection rate (SADR) and advanced adenomadetection rate (AADR). Results: A total of 568 average risk colonoscopies performedby 6 providers were included. Overall PDR was 68.2% in simethicone group versus57.1% in controls (p Z 0.0064, NNT Z 10), figure 1. Right colon PDR was higher for

the simethicone group (51.1% vs. 41.3%, pZ 0.019, NNTZ 11); however, left colonPDR was similar between groups (43.3% vs. 38.9%, p Z 0.286, NNT Z 23). ADR washigher in the simethicone group (56.3% vs. 45.6%, p Z 0.011, NNT Z 10), whereasthe two groups had similar SADR (13.3% vs. 10.7%, p Z .341, NNT: 39) and AADR(14.1% vs. 13.4%, pZ .822, NNTZ 143). The PDR improved for 5 out of 6 providersbut the difference was not statistically significant for individual provider, table 1.Limitation: Small sample size. Adherence to simethicone could not be assessed.Conclusion: Adding simethicone to bowel prep improves polyp and adenoma detec-tion, especially in right colon. To best of our knowledge, this is first study showingimprovement colonoscopy quality with simethicone use in real word clinical prac-tice. We continue to review data on additional patients to strengthen the studyobservations.


ID: 3519117IRRIGATING ACETIC ACID SOLUTION DURINGCOLONOSCOPY FOR THE DETECTION OF SESSILESERRATED NEOPLASIA: A RANDOMIZED CONTROLLEDTRIALGeorge Tribonias*, Angeliki Theodoropoulou, Konstantinos G. Stylianou,Ioannis Giotis, Afroditi Mpitouli, Dimitrios Moschovis, Yoriaki Komeda,Margarita-Eleni Manola, Grigorios Paspatis,Maria TzouvalaBackground and Aims: Misdiagnosed sessile serratedlesions (SSLs) are important precursors for interval colorectal cancers. Weinvestigated the usage of acetic acid (AA) solution for improving thedetection of SSLs in the right colon in a randomized controlled trial.Methods: A tandem observation of the right colon was performed in 412 consecutivepatients. A first inspection was performed under white light high-definition endos-copy. In the AA group, a low concentration vinegar solution (AA: 0,005%) was irri-gated by a water pump in the right colon and it was compared with a plain solution


Abstracts


of normal saline (NS) in the diagnostic yield of SSLs during the second inspection.Secondary outcomes in overall polyp detection were measured. Results: Qualitativecomparisons showed significant differences in the detection rates of all polypsexcept adenomas, with remarkable improvement in the demonstration of advanced(>20mm), SSLs and hyperplastic polyps during the second inspection of the rightcolon using the AA solution. Significant improvement was also noted in the AAgroup, as far as the mean number of polyps/patient detected, not only in SSLs (AAgroup: 0.14 vs NS group: 0.01, P < 0.001), but also in all histological types and allsize-categories in the right colon. Small (� 9 mm) polyps were detected in a higherrate in the sigmoid colon expanding the effect of the method in the rest of thecolon. Conclusion: AA assisted colonoscopy led to a significant increase in SSLsdetection rate in the right colon in a safe, quick and effective manner.

SUNDAY, MAY 23, 2021Colon and Rectum 1Lecture

ID: 3526774IDENTIFICATION OF THE STEPS IN COLD SNAREPOLYPECTOMY THAT LIMIT OVERALL TRAINEECOMPETENCECarmel Malvar*, Tiffany Nguyen-Vu, Rajesh N. Keswani, Swati Patel,Ravishankar Asokkumar, Yungka Chin, Matt Hall, Hazem T. Hammad,Amit Rastogi, Amandeep K. Shergill, Violette C. Simon, Alan Soetikno,Roy M. Soetikno, Sachin B. Wani, Tonya R. KaltenbachBackground: Colonoscopy with polyp detection and removal is a primary driver ofthe observed reductions in colorectal cancer incidence and mortality. However,there has been little focus on the training and assessment of polypectomy techniqueand performance. Previously, we deconstructed the cold snare polypectomy (CSP)technique into its element components to develop and validate the cold snarepolypectomy assessment tool (CSPAT). Herein, we aimed to stratify the CSPATdomains by level of difficulty for trainees to achieve competency in CSP. Methods: Aspart of a randomized control trial on video-based vs conventional apprentice-basedfeedback on CSP learning curves for senior (2nd and 3rd year) trainees rotating at 2tertiary care centers, we video-recorded consecutive polypectomies<1cm in size.Expert raters blindly reviewed randomly assigned videos and assessed CSP perfor-mance overall and for 12 individual domains using the CSPAT; 1-unacceptable, 2-sub-optimal, 3-adequate, 4-perfect. Each trainee received cumulative sum (CUSUM)learning curves at intervals of 25 CSPs. Video-feedback trainees also reviewed videosof their individual CSP alongside gold standard examples. Our primary outcome wasto rank the difficulty of CSP steps based on the number of trainees achievingcompetence (score 3 or 4), and the number of polypectomies needed to reachcompetence across the CSPAT domains. We collected participant, colonoscopy andpolyp characteristics. We determined competence using CUSUM analyses. Results:We enrolled 22 senior trainees to our study. Baseline trainee, colonoscopy and polypcharacteristics are shown in Table 1. Out of the 12 individual CSPAT domains,trainee competence varied (Figure 1). No trainee achieved competence in appro-priate positioning of snare over lesion as snare closed; or in ensuring appropriateamount of tissue is trapped within snare; and few were able to keep the tool close tothe scope or ensure normal rim of tissue is resected around polyp. Moreover, thestep to achieve optimal polyp position required the highest number of CSPs to reach

competence (111.8 � 66.3 CSP; video feedback 122 � 77.3 vs control 91.5 � 53). Incontrast, polyp retrieval had the greatest number of trainees reach competence(nZ13, 59%), after 62.5 � 59.6 polyps; followed by optimizing the polyp view (nZ9,40.9%). Of the 22 trainees, only 2 (9%), both in the video feedback arm, achievedoverall competence after 135 � 134 polypectomies. Conclusion: The learning curvefor CSP is steep and varied among trainees. We identified potential key steps in CSFlimiting trainee competency, including optimizing polyp position, snare positioningand capturing of tissue, and keeping tools close to the scope. Targeted teaching tospecific CSP skills may accelerate skill acquisition and competence across all do-mains. Funded by the ASGE Endoscopy Research Award 2017

SUNDAY, MAY 23, 2021Colon and Rectum 1Poster

ID: 3526558ARTIFICIAL INTELLIGENCE AND COLON CAPSULEENDOSCOPY: AUTOMATIC DETECTION OF COLONICPROTUBERANT LESIONS USING A CONVOLUTIONALNEURAL NETWORKMiguel M. Saraiva*, Helder Cardoso, João Afonso, João Ferreira,Patrícia Andrade, Guilherme MacedoI) Introduction and Objectives: Video capsule colonoscopy (CC) has established it-self as a possible and effective alternative to traditional colonoscopy, in selectedcases. Patients with a high anesthetic risk, whose colonoscopy is not possible tocomplete due to technical difficulties or patients with inflammatory bowel disease,for staging and evaluation of disease activity, can use video capsule methods toassess the colonic mucosa, more conveniently and safely than with traditional co-lonoscopy. The protruding lesions of the colon have a wide variety of presentationsin CC images, so the development of methods for their automatic detection can be


Abstracts


challenging. The clinical relevance of these findings is enormous, not only becausethese lesions can be the source of many complications, but also because their earlydiagnosis is crucial. With this project, we intend to create an Artificial Intelligencemethod capable of automatically detecting the presence of protuberant lesions inthe colonic lumen in CC exams, having outlined the following objectives:i) Acquisition of images containing blood and hematic traces; ii) Development of aConvolutional Neural Network (CNN); iii) Automatic identification of images con-taining blood or hematic traces. II) Material and Methods: A total of 24 CC exams(PillCam Colon 2) from a single-center performed between 2010-2020 wereanalyzed, from which we extracted a total of 765 frames containing protuberant le-sions of the colonic lumen and 2862 frames of normal mucosa. To identify thefindings automatically, these images were inserted into a CNN model with thetransfer of learning using the TensorFlow and Keras tools. Subsequently, we evalu-ated the performance of the network using an independent test set. A schematicrepresentation of the workflow used can be seen in Figure 1. III) Summary ofResults: After optimizing the different layers of the network architecture, it was ableto detect the presence of protuberant lesions, with an accuracy of 97.1%, 95.4%sensitivity, and specificity of 97.3 %. An example of the output obtained can be seenin Figure 2. IV) Conclusions: We have developed a CNN for the automatic detectionof protruding colonic lesions with high accuracy. This development of this type oftool may allow for a better evaluation of these exams, minimizing the error and timenecessary for their observation.


ID: 3522787IMPORTANCE OF OBSERVING DEPRESSED-TYPECOLORECTAL NEOPLASMS IN MAGNIFYINGENDOSCOPY AND ENDCYTOSCOPYShinei Kudo*, Yuki Takashina, Shingo Matsudaira, Kenichi Mochizuki,Yuta Kouyama, Tomoyuki Ishigaki, Katsuro Ichimasa, Kenichi Takeda,Hiroki Nakamura, Naoya Toyoshima, Masashi Misawa, Yuichi Mori,Noriyuki Ogata, Toyoki Kudo, Tomokazu Hisayuki, Takemasa Hayashi,Kunihiko Wakamura, Hideyuki Miyachi, Naruhiko Sawada,Toshiyuki Baba, Fumio IshidaIntroduction: For colorectal carcinomas, “adenoma-carcinoma sequence” theory isgenerally regarded as the leading factor in the development of colorectal carci-nomas. In other words, colorectal carcinomas are caused by polyps. However, theexistence of depressed-type colorectal carcinomas has recently become apparent.These carcinomas are thought to emerge directly from the normal epithelium ratherthan at the adenomatous stage. This theory is called the "de novo" pathway. In thediagnosis of colorectal carcinomas, magnifying endoscopy (pit pattern classification)and endocytoscopy (EC classification) are useful. With these techniques, not onlystructural atypia but also the cellular atypia can be observed in vivo.This time, we decided to clarify the endoscopic characteristics of depressed-typecolorectal carcinomas and demonstrate the validity of pit pattern and EC classifica-tion. Methods: A total of 37146 colorectal neoplasms excluding advanced cancerswere resected endoscopically or surgically in our unit from April 2001 to March2020.Of these, 29413 lesions were low-grade dysplasia, 6391 were high-gradedysplasia and 1342 were submucosally invasive (T1) carcinomas According to thedevelopmental morphology classification, they were divided into 3 types: depressed,flat and protruded-type. We investigated the rate of T1 carcinomas and the charac-teristics of depressed-type neoplasms concerning pit pattern and EC classification.Result: Depressed-type lesions accounted for 62.5% of T1 carcinomas. On the otherhand, the rates of T1 carcinomas with flat-type and protruding lesions were 2.8% and2.7%, respectively. In particular, it was 10%, 0.01%, and 0% for small lesions with adiameter of less than 5 mm, respectively. Most of the flat (91.5%) and protruded-type (94.9%) lesions were type IIIL or IV, which refers to adenomas in the pit patternclassification. Most of the depressed-type lesions (92.2%) were type IIIS, VI or VN,which refers to carcinoma in the pit pattern classification. For endoscopy, most ofthe flat and protruding lesions were EC2, which refers to adenomas in the ECclassification. In contrast, the depressed lesions were EC3a (37.0%) and EC3b(55.6%), which in the EC classification refer to invasive cancers. Conclusion: Thistime, we have clarified the diagnostic characteristics depressed-type lesions.Most of the depressed-type lesions were diagnosed as invasive cancer by magnifyingendoscopy or endocytoscopy. In addition, since lesions tend to infiltrate the sub-mucosa regardless of size, it is important to perform magnifying endoscopy andendocytoscopy even if the lesion is small.


ID: 3521050HOW TO DIAGNOSE TUMOR DIFFERENTIATION AS ARISK FACTOR FOR LYMPH NODE METASTASIS IN T1COLORECTAL CANCER?Katsuro Ichimasa*, Shinei Kudo, Hideyuki Miyachi, Yuta Kouyama,Shingo Matsudaira, Kenichi Mochizuki, Yuki Takashina, Hiroki Nakamura,Tomoyuki Ishigaki, Naoya Toyoshima, Yuichi Mori, Masashi Misawa,Noriyuki Ogata, Toyoki Kudo, Tomokazu Hisayuki, Takemasa Hayashi,Kunihiko Wakamura, Toshiyuki Baba, Fumio IshidaBackground: Tumor differentiation is one of the important risk factors for lymphnode metastasis in T1 colorectal cancer, which is referred to in several guidelinessuch as US, European and Japanese. If poorly differentiated adenocarcinoma, signet-ring cell carcinoma or mucinous carcinoma are observed during histological evalu-ation of the endoscopically resected specimens, intestinal resection with lymphnode dissection is recommended as an additional treatment. However, the way todiagnose the tumor differentiation is different among these guidelines (least dif-ferentiation in US guidelines, predominant differentiation in Japanese guidelines).The aim of this study is to determine which is more effective method in risk strat-ification of lymph node metastasis, predominant or least differentiation analysis.Methods: We initially evaluated the consecutive 853 patients with T1 colorectal can-cer who underwent initial or additional surgical resection with lymph nodedissection from 2001 to 2019 at our institution, for inclusion in this retrospectivestudy. We then excluded those who had (a) synchronous or metachronous


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advanced cancer, (b) invasion to the muscularis propria or deeper in surgicalspecimens, (c) familial adenomatous polyposis, Lynch syndrome or ulcerative colitis,(d) preoperative chemotherapy or radiotherapy, or (e) missing data. Finally, weenrolled 805 patients in this study. We evaluated tumor differentiation in twomethods (predominant or least) and divided into low-risk (well or moderatelydifferentiated adenocarcinoma, or papillary adenocarcinoma) and high-risk (poorlydifferentiated adenocarcinoma, signet-ring cell carcinoma or mucinous carcinoma)in each method. The correlation between two patterns of differentiation analysis(predominant or least) and the rate of lymph node metastasis was investigated.Operative specimens were used as the gold standard for the presence of lymphnode metastasis. Results: Lymph node metastasis was found in 9.7% (78/805). Ratesof high-risk cases in predominant and least analysis were 0.7% (6/805) and 16.3%(131/805), respectively. Sensitivity, specificity, and area under the receiver operatingcharacteristics curve for lymph node metastasis in predominant and least analysiswere 2.6%, 99.4%, 0.50 and 28.2%, 85.0%, 0.56, respectively. Conclusion: Least dif-ferentiation analysis would be more reliable in predicting the risk of lymph nodemetastasis in T1 colorectal cancer than predominant differentiation analysis.


ID: 3522221SYSTEMATIC REVIEW AND META-ANALYSIS OF COLONCAPSULE ENDOSCOPY ACCURACY FOR COLORECTALCANCER SCREENING. AN ALTERNATIVE DURING THECOVID ERA?Marianny Sulbaran*, Wanderley M. Bernardo,Leonardo A. Bustamante-Lopez, Christiano M. Sakai, Paulo Sakai,Sergio C. Nahas, Eduardo G. De MouraBackground and Aim: Compliance to colorectal cancer screening remainssuboptimal. Barriers that limit patient’s adherence to colonoscopy screening havegrown during Covid-19 pandemic. Less invasive technologies, such as colon capsuleendoscopy may serve as an alternative approach.The aim of this study is todetermine the diagnostic accuracy of colon capsule endoscopy compared tocolonoscopy for colorectal cancer screening. Methods: A systematic review andmeta-analysis of studies in which the outcomes of colonoscopy and second gener-ation colon capsule endoscopy (CCE-2) for screening of asymptomatic patients olderthan 50 years oldwere compared. The primary outcomes were sensitivity, specificity,positive and negative likelihood ratios for polyps and adenomas larger than 6mmand 10mm. Results: There were 6 full-text studies that evaluated 1312 patientsincluded for systematic review. Of these, 695 (53%) patients participated of anopportunistic program. The pooled outcomes of CCE-2 for polyps larger than 6mmwere: Sensitivity: 0.87 (95% confidence interval: 0.825 – 0.908), with heterogeneity3.69 (p Z 0.29), inconsistency Z 18.8%; Specificity: 0.94 (95% confidence interval:0.92 – 0.96), with heterogeneity 24.05 (p Z 0.001), inconsistency Z 87.5%; Positivelikelihood ratio: 11.11 (95% confidence interval: 3.7 – 33.32), with heterogeneity34.13 (p Z 0.001), inconsistency Z 91.2%; Negative likelihood ratio: 0.15 (95%confidence interval: 0.11 – 0.2), with heterogeneity 1.9 (p Z 0.59), inconsistency Z0.1%. The pooled outcomes of CCE-2 for polyps larger than 10mm were:Sensitivity: 0.86 (95% confidence interval: 0.78 – 0.92), with heterogeneity 0.62 (pZ0.7), inconsistency Z 0.1%; Specificity: 0.98 (95% confidence interval: 0.96 – 0.99),with heterogeneity 3.08 (p Z 0.22), inconsistency Z 35%; Positive likelihood ratio:35.45 (95% confidence interval: 19.54 – 64.34), with heterogeneity 3.36 (p Z 0.31),inconsistency Z 15.2%; Negative likelihood ratio: 0.15 (95% confidence interval:0.09 – 0.23), with heterogeneity 0.53 (p Z 0.77), inconsistency Z 0.1%.The area under the curve of the summary receiver operating characteristic curve forpolyps larger than 6 and 10mm was 0.95 and 0.94 respectively (Figure 1 and 2). Theonly cancer missed by complete CCE-2 was shown at multiple frames in the un-blinded review. In total, 122 (9.3%) patients presented mild adverse events mostlyrelated to bowel preparation. Conclusion: CCE-2 is an accurate and safe screeningalternative for colorectal neoplasia, and its application may potentially improve ac-cess to screening, facilitating the detection of early colorectal lesions.

Figure 1. SROC curve for CCE-2 diagnosis of polyps > 6 mm.

Figure 2. SROC curve for CCE-2 diagnosis of polyps > 10 mm.


ID: 3523488BLOOD TEST INCREASES COLORECTAL CANCERSCREENING UPTAKE IN INDIVIDUALS WHO HAVEDECLINED COLONOSCOPY AND FECALIMMUNOCHEMICAL TESTING: A RANDOMIZEDCONTROLLED TRIALPeter S. Liang*, Anika Zaman, Anne M. Kaminsky, Yongyan Cui,Gabriel Castillo, Craig T. Tenner, Scott E. Sherman, Jason A. DominitzIntroduction: The only FDA-approved blood test for colorectal cancer screening,which detects methylated SEPT9 DNA, is indicated for those who have declinedfirst-line screening tests. However, the impact of this test on screening uptake in thisscreen-resistant population is unknown. We conducted a randomized controlled trialto compare outreach with re-offer of colonoscopy and fecal immunochemical test(FIT) alone (control) vs. adding the option of a blood test (intervention) in indi-viduals who have previously declined colonoscopy and FIT. Methods: Screen-eligibleVeterans aged 50-75 years with documented refusal to colonoscopy and FIT withinthe previous six months were randomized 1:1 to the intervention and control


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groups. Outreach consisted of a mailed letter followed by up to five calls. Thecontrol group was informed of being overdue for screening and was recommendedto undergo colonoscopy or FIT as first-line options. The intervention group receivedthe same information, but was also told that if they declined colonoscopy and FIT, ablood test would be available as an option. Those who preferred colonoscopy or FITwere referred for testing. The primary outcome was the proportion who receivedany screening within six months of outreach. The secondary outcome was theproportion who completed a full screening strategy (i.e., including colonoscopy forthose with a positive FIT or blood test) within six months. Results: In total, 359patients completed six months of follow-up. For the primary outcome, screeningoccurred in 19 of 178 (10.7%, 2 colonoscopy, 17 FIT) in the control group and 33 of181 (18.2%, 5 colonoscopy, 17 FIT and 11 blood test) in the intervention group(PZ0.04). Test positivity was 8.8% for FIT and 18.2% for the blood test. For thesecondary outcome, 10.1% of the control group and 15.5% of the intervention groupcompleted a screening strategy (PZ0.13). Four of five patients with positive FIT orblood tests did not complete colonoscopy within six months of outreach. In aCOVID-related sensitivity analysis that excluded patients whose initial outreachoccurred within six months of the first confirmed case in our city, 15 of 157 (9.6%) inthe control group and 32 of 161 (19.9%) in the intervention group completed anyscreening (PZ0.01). Conclusions: Among screen-resistant individuals who havepreviously declined colonoscopy and FIT, offering a blood test as a secondary optionincreased screening by 8%. Importantly, there was no decrease in colonoscopy orFIT use in those given the blood test option. These results suggest that a subset ofthose who have declined first-line screening options may be receptive to a bloodtest. Since the majority of participants remained unscreened, additional interven-tions are needed to encourage screening. Ensuring diagnostic evaluation after apositive non-invasive test also remains a challenge and priority.


ID: 3521853CLINICAL AND PATHOLOGICAL CHARACTERISTICS OFDEPRESSED-TYPE COLORECTAL NEOPLASMSShinei Kudo*, Kazumi Takishima, Yuta Kouyama,Katsuro Ichimasa, Naoya Toyoshima, Yuichi Mori, Masashi Misawa,Toyoki Kudo, Noriyuki Ogata, Tomokazu Hisayuki, Kunihiko Wakamura,Takemasa Hayashi, Toshiyuki Baba, Fumio IshidaAbstract body: Colorectal neoplasms are divided into three morphological types:depressed-type, flat-type and protruded-type. We aimed to investigate clinical andpathological characteristics and long-term prognosis of depressed-type colorectalneoplasms, considered as “de novo” pathway, which is considered to emergedirectly from normal epithelium, not through the adenomatous stage. Method: Atotal of 37,146 colorectal neoplasms excluding advanced cancers were resectedendoscopically or surgically in our center from April 2001 to December 2019. Ofthese, 1,342 lesions were T1 carcinomas. According to the developmentalmorphology classification, they were divided into 3 types: 294 lesions (21.9%) weredepressed-type, 481 lesions (35.8%) were flat-type and 566 lesions (42.1%) wereprotruded-type. We analyzed the pathological difference of these lesions. Resultsand Discussion: Among T1 carcinomas, the rates of vessel invasion were 48%, 22% and21%, that of poorly differentiated ormucinous adenocarcinomawas 16%, 10% and 14%,that of massively submucosal invasion was 94.5%, 71.3% and 77.5%, and that of tumorbudding was 34.5%, 14.8% and 16.9%, respectively. The rates of these pathologicalfactors were significantly higher in depressed-type lesions than other types. On theother hand, the rate of adenomatous component was 5.1%, 56.7% and 51.5%, and therate of polypoid growth was 13.8%, 57.4% and 96.4% respectively. It was significantlylower in depressed-type lesions, suggesting that they emerge directly from normalepithelium without going through the adenomatous stage. The rates of lymph nodemetastasis were 8.7%, 3.1% and 10.2%, respectively, in which no significant differencewas found in these three types. The rate of distant metastasis or recurrence was 1% (10/1,342). Among these 10 cases, 5 cases were depressed-type lesions among which oneshowed a para-aortic lymph node metastasis and four showed a lung metastasis.Conclusions: Depressed-type colorectal neoplasms contained malignant clinical andpathological characteristics. Detection and precise diagnosis of depressed-type colo-rectal neoplasms is important in the treatment of colorectal carcinomas.


ID: 3520607YOUNGER PATIENTS DO NOT DEVELOP HIGHERGRADE POLYPS ON SURVEILLANCE COLONOSCOPYTHAN THEIR INDEX COLONOSCOPY WHEN COMPAREDTO OLDER PATIENTSJoseph Mizrahi*, Kushang Shah, Adam Myer, Michelle Sheyman, Karl Meir,Katey-Rose Redhead, Olga C. Aroniadis, Deepak Desai, Grace GathunguIntroduction: Over the past several decades, the incidence of Colorectal Cancer (CRC)in the United States has been decreasing for patients older than 50, but increasing forpatients younger than 50. While this trend has prompted a recent update to CRCscreening guidelines to start at age 45 as oppose to 50, current colonic polyp surveil-lance guidelines are still based on data only from older patients. We thus sought toinvestigate whether existing colonic polyp surveillance guidelines are appropriate touse in younger patients who have polyps resected during colonoscopy. Methods: Weperformed a retrospective cohort study with patients recruited from two academicmedical centers who underwent two colonoscopies with at least one polyp resectedwithin a 10-year period. Five Risk Stratification Groups (RSG) were developed basedon surveillance colonoscopy interval times recommended by the USMSTF on CRC(Table 1). RSGs were assigned to patients as determined by the size, number, andpathology of polyps resected during a patient’s colonoscopy, and changes in RSG fromindex to surveillance colonoscopy were compared between older and younger pa-tients. Two separate analyses were done with age cutoffs at 45 and 50 given the recentchange in guidelines. Further analysis was performed for patients whose RSG wors-ened from index to surveillance colonoscopy, as having higher grade polyps on sur-veillance colonoscopy compared to their index colonoscopy may signify aninappropriate surveillance interval. Results: 1895 patients were included in the finalanalysis, with 371 patients younger than 50 and 167 patients younger than 45. Patientsyounger than 50 had a higher rate of RSGworsening (31.54%) compared to those olderthan 50 (25.67%), but patients younger than 45 had a slightly lower rate of RSGworsening (25.75%) compared with patients older than 45 (26.92%). Multivariateregression analysis showed no significant association between RSGworsening and ageat either the age 50 cutoff (ORZ1.23, 95% CI: 0.949 – 1.606) or at the age 45 cutoff(ORZ0.86, 95% CI: 0.589 - 1.253), but did find RSG worsening to be significantlyassociated with gender and indication for the procedure (Table 2). Conclusion: Ourstudy suggests that younger patients, at both an age 45 and an age 50 cutoff, did not


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significantly develop higher grade polyps on surveillance colonoscopy than theirindex colonoscopy, when compared to older patients. This would imply that despitesurveillance guidelines being developed based solely on data from older patients,these same guidelines are indeed appropriate to use for younger patients in whomcolonic polyps are found. As more younger patients undergo screening colonos-copies, more polyps are inevitably going to be found, and thus further study iswarranted regarding how to appropriately surveil this unique subset of patients.


ID: 3525491ALCOHOL CONSUMPTION AND COLORECTALADENOMA - A DOSE-DEPENDENT RELATIONSHIPGeorg Semmler*, Sarah Wernly, Sebastian Bachmayer,Matthias Egger, Lena Schwenoha, Leonora Datz, Lorenz Balcar,Marie Semmler, Felix Stickel, Elmar Aigner, David Niederseer,Christian DatzBackground and Aims: Although several lifestyle factors such as obesity, factors of themetabolic syndrome, physical activity, smoking, and consumption of red meat havebeen identified asmodifiable risk factors for colorectal adenoma and colorectal cancer,the role of alcohol consumption remains controversial. Specifically, low or moderatelevels have been considered “safe” due to inconclusive results from published studies.We therefore aimed to clarify the role of alcohol consumption on the prevalence ofcolorectal lesions. Methods: 5478 patients undergoing colonoscopy were included aspart of a colorectal carcinoma colonoscopy screening program. Patients were char-acterized using biochemical and metabolic parameters. Data on alcohol consump-tion was extracted from detailed food frequency questionnaires and denoted asgramm (g)/week. For group comparison, patients were stratified according to theiralcohol consumption into 0g/week, 0-70g/week, 70-140g/week, 140-210g/week and>210g/week. Colorectal neoplasia were classified macroscopically and histologicallyas hyperplastic polyps, adenomas, advanced adenomas and colorectal cancer.Results: 53.3% of patients were male with a mean age of 58.4�9.6 years and a meanBMI of 27.1�4.7kg/m̂2. The metabolic syndrome was present in 2151 (42.8%) pa-

tients. Overall, any polyp was present in 1622 patients (29.6%), any adenoma in 1753patients (32.0%) and any advanced adenoma in 410 patients (7.5%). 2051 (37.4%)did not regularly consume alcohol, 1162 (21.2%) consumed 0-70g/week, 1130(20.6%) consumed 70-140g/week, 674 (12.3%) consumed 140-210g/week and 461(8.4%) consumed >210g/week regularly. Among these groups, prevalence increasedlinearly for any adenoma (28.8% vs. 29.7% vs. 32.6% vs. 38.0% vs. 42.1%, p<0.001)and any advanced adenoma (6.3% vs. 6.7% vs. 6.9% vs. 9.6% vs. 12.8%, p<0.001). Onmultivariable linear regression analyses correcting for established risk modifiers suchas age, gender, BMI, family history, hypertension, diabetes, fatty liver disease,smoking, physical activity and dietary patterns, consumption of alcohol was inde-pendently associated with the presence of adenoma (adjusted Odds ratio [aOR] per10g/week: 1.007, 95% confidence interval [CI]: 1.001-1.014, pZ0.039), and advancedadenoma (aOR: 1.011, 95%CI: 1.001-1.022, pZ0.033). Conclusion: We demonstratean independent linear relationship between alcohol consumption and the risk forcolorectal adenoma. Thus, even low or moderate amounts of alcohol mightcontribute to the risk profile for colorectal adenoma.


ID: 3522605ARE WE READY TO ADOPT "DIAGNOSE-AND-LEAVE"STRATEGY: NOT SO FAST. A MULTICENTERINTERNATIONAL EXPERIENCEDimpal Bhakta*, Jigar Patel, Carlos Cifuentes, Prithvi Patil, Asmeen Bhatt,Haydee Alvarado, Juan M. Alcívar-Vásquez, Raquel S. Del Valle,Roberto Oleas, Ricardo Badillo, Shahrooz Rashtak, Srinivas Ramireddy,Tomas DaVee, Carlos Robles-Medranda, Sushovan Guha, Nirav ThosaniBackground: Real-timeoptical assessment is increasingly utilized and recommendedbyguidelines. Given overall low prevalence of malignancy in small hyperplastic left-sidedcolon polyps, “Diagnose-and-Leave” strategy is currently under investigation as a cost-effective approach to themanagementof colonpolypsdue to its reduction inproceduretime and costs related to histopathology. Methods: We conducted a prospectivemulticenter international trial onoptical assessment of colon polyps and comparedfinalresults against histopathology as gold standard between June 2020 to November 2020.There were nine experienced gastroenterologists who performed these colonoscopiesand evaluated polyps using high-definition white light endoscopy as well as i-Scan op-tical enhancement (i-ScanOE) technology.When a colorectal polypwas identified, eachprovider was asked to provide their optical diagnosis (adenoma, hyperplastic, sessileserrated) and overall confidence level (high or low). Data were prospectively collectedin the electronic Redcap software. Optical assessment results were then comparedagainst the final histopathology of the colorectal polyps. Results: A total of 339 polypswere evaluated during the study period. Final histopathology showed 227 adenoma-tous, 100 hyperplastic and 12 sessile serrated polyps. For adenomatous polyps, overalldiagnostic accuracywas 85.9% (Range66%-100%).Whenanalysiswas restricted to “highconfidence” during optical assessment, overall accuracy increased to 88%. Overall ac-curacy decreased to 74% when analysis was limited to polyp size< 5mm. In contrast toadenomatouspolyps, overall diagnostic accuracy for hyperplastic polypswas very low at64% (Range 38%-100%). Even when analysis was restricted to “high confidence”, diag-nostic accuracy for hyperplastic polyp only increased to 67%. For polyps< 5mm in size,overall diagnostic accuracy for hyperplastic polypwas 77% and it improved to 82%whenoptical assessment was done with high confidence. We had limited number of sessileserrated polyp in this study and overall diagnostic accuracy was 58.3%. Conclusion: Ourfindings suggest that although experienced gastroenterologists are skilled at predictingadenomatous polyps (88% accurate with high confidence), their performance remainspoor in accurately diagnosing hyperplastic and sessile serrated polyps. Adoption of“Diagnose-and Leave” strategy for < 5 mm size polyps would have resulted in non-removal of close to 20% of possible precancerous polyps.


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COLON AND RECTUM 1 · 2021. 5. 14. · COLON AND RECTUM 1 FRIDAY, MAY 21, 2021 Colon and Rectum 1 Poster ID: 3526203 EFFICACY AND SAFETY OF COLD SNARE POLYPECTOMY (CSP) OF INTERMEDIATE