Appor t de I ' endosonograph ie dans le c a n c e r de I 'anus

V. DE PARADES *, T. BOUILLET **, C. PARISOT *, P. ATIENZA *

�9 Service de proctologie rnOdico-chirurgicale �9 * HOpital de jour

HOpital des Diaconesses, Paris (France)

The role of endosonography in anal cancer

RI~SUMt2

L'endosonographie est un outil performant, de mise au point r6cente, plus fiable que l'examen clinique et la tomodensitomdtrie, prd- sentant de nombreux int6r&s en pathologie tumorale anale. Elle permet d'obtenir un bilan d'extension tumorale et ganglionnaire satisfaisant et la ddtection d'un r~sidu tumoral ou une rdcidive 6ventuelle apr6s traitement. Elle devrait bdndficer de l'apport des ponctions cytologiques et/ou biopsies 6cho-guid6es. Son impact thdrapeutique peut 6tre majeur : chimiothdrapie adjuvante ~ la radiothdrapie en cas de tumeur volu- mineuse et/ou en cas d'ad6nopathies supposdes envahies, contre-indication 5 une curiethdrapie en cas d'addnopathies envahies, radiothdrapie de surdosage ou amputation abdomino-pdrindale en cas de rdsidu tumoral ou de rdcidive.

S UMMA R Y

The technique o f endosonography has only recently been developed. It is more reliable than clinical examination and tomodensitometry, and is thus valuable for in vestigating anal tumors, h can be used to assess o f local minor in vasion and lymph node spread and for the detection o f residual or recurrent tumors after treatment. Another useful application is its use to obtain ultrasound-guided aspiration. It could have major therapeutic impact: chemotherapy combined with radiotherapy for voluminous tumors and~or lymph nodes" suspected to be invasive, cases o f metastatic lymph nodes for which radium therapy is contraindicated, cases o f residual or recurrent ttsmor~ for which high dose radiation therapy or abdominal-perineal amputation is indicated.

INTROD UCTION

L'endosonographie est une technique r6cente qui est la premiere ~ nous avoir fourni une image anato- mique satisfaisante du canal anal. Elle conna~t un essor considdrable depuis dix ans qui a 6t6 favoris6 par les insuffisances de l'examen clinique, de I'6cho- graphie transparidtale ou de la tomodensitomdtrie. En outre, elle est simple fi rdaliser, peu co0teuse, reproductible et ddnu6e d'effets secondaires.

Largement diffus6e dans le cadre de l'incontinence anale o~ elle permet de visualiser les ruptures sphinc- t6riennes [1], elle a 6t6 peu 6tudi6e en pathologie tumorale de l'anus [2]. Pourtant, les intdr~ts poten- tiels de l 'endosonographie dans ce cadre patholo- gique sont majeurs, pouvant rev~tir une importance ddcisive en terme de choix thdrapeutique. Cette mise au point a pour but de prdciser les apports de l'endo- sonographie dans la prise en charge du cancer du canal anal sachant sa principale limite, fi savoir l'ab- sence de validation histo-pathologique des constata-

tions 6chographiques puisque les patients ont 6t6 trai- t6s par radioth6rapie dans la plupart des s6ries publi6es.

M A T E R I E L

La sonde rigide, que l'on introduit ~ l'aveugle dans le canal anal jusqu'~ la charni6re recto-sigmoidienne, a 6t6 le premier mat6riel mis au point. L'extr6mit6 de cette sonde peut ~tre recouverte par un ballonnet rempli d'eau d6gaz6e qui fournit une interface acous- tique entre le transducteur et la paroi pour l'6tude du rectum. Elle peut 6galement ~tre recouverte par un c6ne rigide 6cho-transparent, de 10 ~ 23 mm de dia- m6tre, rempli d'eau d6gaz6e pour l'6tude du canal anal [3].

L'6choendoscope souple est apparu plus r6cem- merit. Son extr6mit6, dont le diam6tre varie de 12 17 ram, recouverte par un ballonnet, est b6quillable, permettant d'orienter le faisceau ultrasonore et

Tir6s-h-part : Vincent de PARADES. H6pital des Diaconesses, 18, rue du Sergent-Bauchat, F-75012 Paris (France).

Mots-cl~s: anus, cancer, diagnostic, endosonographie, traitement.

Key-words: anus, cancer, diagnostic, endosonography, treatment.

Acta Endoscopica Volume 28 - N ~ 4- 1998 359

d'aller au-del~ de la charni6re recto-sigmo]'dienne. C'est un appareil plus cofiteux que la sonde rigide et le ballonnet, en raison de sa compliance limit6e, peut g6ner l'6tude du canal anal [4].

La fr6quence utilis6e en pratique courante au niveau du canal anal et du rectum varie de 5 10 MHz.

TECHNIQUE

Apr6s avoir effectu6 un lavement 6vacuateur, le patient ambulatoire est install6 en position gyn6colo- gique ou en d6cubitus lat6ral. Les images sont 6tu- di6es au fur et ~ mesure du retrait doux et progressif de la sonde [3, 4]. L'exploration dchographique peut 6tre men6e par voie endo-vaginale, no tamment en cas de st6nose anale infranchissable ou apr~s amputa- tion abdomino-p6rin6ale [5]. Rarement, des douleurs peuvent imposer une s6dation [6, 7].

L ' image 6chographique obtenue est tranversale, sur 270 ~ 360 ~ de la circonf6rence, perpendiculaire l 'axe de la sonde lorsqu'il s'agit des sondes m6ca- niques rotatives axiales. L'image est sagittale, paral- 161e ~ l'axe de l'appareil lorsqu'il s'agit d 'une sonde 61ectronique [3, 4].

INT[~RETS DE L'IE.CHOGRAPHIE

1) Diagnostic positif

L'aspect 6chographique d 'une tumeur anale est celui d 'une masse hypo6chog6ne ou hyper6chog6ne, plus ou moins h6t6rogbne, mal limit6e, situ6e dans la paroi du canal anal, pouvant s '6tendre vers les organes de voisinage [6-10]. Cependant, cet aspect n'est pas sp6cifique et l 'endosonographie ne peut dis- t inguer une tumeur maligne (Fig.l, 2 et 3) d 'une

tumeur b6nigne, d 'un lymphome ou d 'un abc6s (Fig. 4). La confirmation anatomo-pathologique reste donc indispensable.

2) Bilan loco-r~gional pr~-th~rapeutique

Extension tumorale

L'endosonographie permet de pr6ciser le site de la tumeur, sa taille, son extension en hauteur, sur la cir- conf6rence et en profondeur vers le sphincter anal, le vagin, la prostate ou les v6sicules s6minales [6-11]. I1 faut souligner la sup6riorit6 de l 'endosonographie sur l 'examen clinique pour l'6valuation de l'extension en profondeur. Dans la s6rie prospective de 50 carci- nomes 6pidermoides de Goldman et colL, l 'examen clinique avait m6connu une extension au-dela du sphincter interne dans 63 % des cas [10].

Une classification 6chographique a 6t6 mise au point [6, 10]:

- - UT1 : tumeur limit6e ~ la muqueuse et h la sous- muqueuse (Fig. 1) ;

- - UT2 : tumeur limit6e au sphincter interne au dessous du puborectal et/ou h la musculeuse rectale au dessus ;

- - UT3: tumeur d6passant le sphincter interne et/ou la musculeuse rectale (Fig. 2 et 3) ;

- - UT4 : extension a un organe de voisinage.

Extension ganglionnaire

Les ganglions normaux sont le plus souvent non visualis6s en endosonographie. Les ad6nopathies sont suppos6es m6tastatiques si elles sont iso6cho- g6nes h la tumeur ou hypo6chog6nes, rondes, bien limit6es, mesurant plus de 5 ~ 10 mm. Cependant , d 'authent iques ad6nopathies envahies, mesurant moins de 5 mm, peuvent ne pas ~tre visualis6es. En

Figure 1 Carcinome anal in situ UT1 : zone hypo6chogene antero-gauche situ6e dans la premiere couche hyperechogene (coupe transversale) (sonde

Bruel and Kjaer) Anal carcinoma in situ UT1 : hypoechoic area in the hyperechoic first

layer (transverse image) (Bruel & Kjaer probe)

Figure 2 Carcinome anal UT3 : zone hypoechogene posterieure d6passant

largement le sphincter interne (coupe transversale) (sonde Bruel & Kjaer) Anal carcinoma UT3 : posterior hypoechoic area extending beyond

the internal sphincter (transverse image) (Bruel & Kjaer probe)

360 V o l u m e 2 8 - N ~ 4 - 1998 A c t a E n d o s c o p i c a

Figure 3 Carcincme UT3 : zone hyper~chogene anterieure, mal limitee, depassant

largement le sphincter interne (transverse image) (sonde Bruel & Kjaer) Anal carcinoma UT3 : anterior hyperechoic area extending beyond the

internal sphincter (transverse image) (Bruel & Kjaer probe)

Figure 4 Abces intramural post&ieur (coupe transversale) (sonde Bruel & Kjaer)

Posterior intersphincteric abcess (transverse image) (Bruel & Kjaer probe)

Figure 5 Adenopathie ronde, hypoechogene, bien iimitee, para-rectale gauche, de

7 mm de diam~tre, supposee metastatique (coupe transversale) (sonde Bruel & Kjaer)

Round, hypoechoic, perirectal lymph node with well-defined edges, measuring 7 mm, supposed to be metastatic (transverse image)

(Bruel & Kjaer probe)

Figure 6 Adenopathie ronde, & centre hyperechogene, para-rectale gauche, de

6 mm de diam~tre, supposee inflammatoire (coupe transversale) (sonde Bruel & Kjaer)

Round, hyperechoic, perirectal lymph node, measuring 6 mm, supposed to be inflamed (transverse image) (Bruel & Kjaer probe)

outre, distinguer une ad6nopathie envahie (fig. 5) d'une ad6nopathie inflammatoire rdactionnelle (fig. 6) reste difficile en 6chographie [6, 7, 9, 12].

Au mSme titre que pour les tumeurs du rectum, la sensibilit6 et la sp6cificit6 du bilan ganglionnaire n6cessitent donc d'Stre am61ior6es [13, 14]. Les ponc- tions cytologiques et/ou les biopsies 6cho-guid6es, permettant d'affirmer le caractSre envahi d'une ad6- nopathie, constituent une avanc6e en la matibre [15, 16].

Consequences th~rapeutiques du bilan loco-r~gional

Le bilan d'extension loco-r6gional a un int6r6t majeur sur le plan th6rapeutique. En effet, il permet

de proposer une chimioth6rapie adjuvante ?~ la radioth6rapie aux patients ayant une grosse tumeur (UT3 ou UT4). De mSme, la pr6sence d'ad6nopa- thies para-rectales satellites peut non seulement amener h 61argir le champs d'irradiation et proposer une chimioth6rapie adjuvante mais contre-indique 6galement une curieth6rapie illogique. Ces donn6es m6ritent d'Stre confirm6es par des 6tudes contr6- 16es.

3) Evaluation du pronostic

L'int6rSt de l'endosonographie dans ce domaine 6tait attendue puisqu'on savait que le pronostic des cancers de l'anus est ii6, entre autres,/a la taille de la tumeur et/i l'existence d'ad6nopathies [17].

A c t a E n d o s c o p i c a V o l u m e 28 - N ~ 4 - 1998 361

Goldman et coll. ont ainsi 6tabli une corr61ation significative (tableau I) entre le bilan endosonogra- phique d'extension tumorale et la r6ponse au traite- merit [10]. Cette corrdlation a 6t6 confirmde [6, 18] mais 6galement contestde [7, 19]. D'autre part, Fran- cois et coll. ont 6tabli une corr61ation significative (tableau II) entre la pr6sence ou non d'ad6nopathies en 6chographie et la rdponse au traitement [18], don- n6e confirm6e par Giovannini et coll. [19].

TABLEAU I

CORRI~LATION ENTRE LE BILAN ENDOSONOGRAPHIQUE D'EXTENSION TUMORALE ET

LA Rt~PONSE AU TRAITEMENT (P < 0,05) [10]

Extension Taille (cm) n

UT1-2 < 5 / 13 UT3-4 < 5 l 22 UT3-4 > 5 11

R6ponse au traitement (%)

100 64

0

De mSme, elle peut dOtecter les r6cidives locales apr6s traitement et son efficacit6 serait sup6rieure celle de la tomodensitom6trie [6-8, 20]. Cependant, il n'a pas 6t6 dOmontr6 qu'elle les dOpiste plus pr6coce- ment que l'examen clinique [20, 21]. En outre, la radioth6rapie est ~a l'origine de remaniements tissu- laires (oed6me, n6crose, fibrose) dont l'aspect 6cho- graphique : 6paississement de la paroi rectale pr6do- minant au niveau de la musculeuse (Fig. 7) ou ilOts hypo ou hyper6chog6nes, situ6s darts la paroi rectale ou l'atmosph~re p6ri-rectale, peut mimer une r6ci- dive tumorale ou ganglionnaire (Fig. 8 et 9). L'aug- mentation de taille lors de deux examens successifs est un fort argument pour une tumeur 6volutive. Dans ce cas, les biopsies 6cho-guid6es constituent encore un apport d6cisionnel majeur en affirmant le

TABLEAU I1

CORRI~LATION ENTRE LE BILAN ENDOSONOGRAPHIQUE D'EXTENSION

GANGLIONNAIRE ET LA RI~PONSE AU TRAITEMENT (p = 0,03) [181

Extension n Rdponse au traitement (%)

N - 22 68 N + 13 23

4) D~tection d'un r~sidu tumoral ou d'une r~cidive

L'endosonographie, apr~s traitement m6dical, peut visualiser la persistance 6ventuelle d'un r6sidu tumo- ral ou d'addnopathies amenant ~ discuter une radio- thdrapie de surdosage ou une amputation abdomino- p6rin6ale de << rattrapage ,, [6, 7, 10].

Figure 8

Recidive tumorale parietale : zone hypoechogene, bien limit6e, antero- gauche, envahissant toute I'epaisseur de la paroi rectale (coupe transver-

sale) (sonde Bruel & Kjaer) Rectal recurrent tumor : an hypeechoic area with well-defined edges

disrupt the rectal wall (transverse image) (Bruel & Kjaer probe)

Figure 7

r heterogene et irr6gulier de la musculeuse rectale sequellaire d'une radiotherapie (coupe transversale) (sonde Bruel & Kjaer)

Heterogeneous and irregular thickening of the muscularis propria after radiotherapy (transverse image) (Bruel & Kjaer probe)

Figure 9

Recidive tumorale ganglionnaire para-rectale : zone hypo6chog~ne, polylobee, bien limitee, post6ro-gauche (coupe transversale)

(sonde Bruel & Kjaer) Rectal recurrent lymph node : hypoechoic perirectal area with well-

defined edges (transverse image) (Bruel & Kjaer probe)

362 V o l u m e 2 8 - N ~ 4 - 1 9 9 8 Acta Endoscopica

diagnostic de r6cidive tumorale, ~ priori n6cessaire avant toute d6cision de radioth6rapie de surdosage ou d'amputation abdomino-p6rin6ale [5-7, 20, 21].

En pratique, la plupart des auteurs pr6conise d'ef- fectuer une endosonographie de surveillance tous les trois ~a quatre mois pendant au moins les deux pre- mitres ann6es.

CONCL USION

L'endosonographie est donc un outil performant, plus fiable que l'examen clinique et la tomodensito- m6trie, pr6sentant de nombreux int6rSts en patholo- gic tumorale anale, Elle permet d'obtenir un bilan d'extension tumorale et ganglionnaire satisfaisant. Cela d'autant plus d'importance que deux 6tudes ran- domis6es r6centes ont bien ddmontr6 la sup6rioritd significative de la radio-chimiothdrapie sur la radio-

th6rapie seule dans les tumeurs class6es T3-4 N0-3 ou T1-2 N1-3 en termes de taux de contr61e loco-r6gio- nal, de conservation sphinct6rienne et de rechute locale [22, 23]. En outre, elle permet une 6valuation pronostique et la d6tection d'un r6sidu tumoral ou une r6cidive 6ventuelle apr6s traitement. Elle devrait b6n6ficer de l'apport des ponctions cytologiques et/ou des biopsies 6cho-guid6es pour affirmer le caract6re envahi d'une ad6nopathie ou une r6cidive. Cependant, son int6rSt d6cisionnel sur le plan th6ra- peutique : chimioth6rapie adjuvante en cas de tumeur volumineuse et/ou en cas d'ad6nopathies suppos6es envahies, contre-indication h une curieth6rapie en cas d'ad6nopathies envahies, radioth6rapie de surdosage ou amputation abdomino-p6rin6ale en cas de r6sidu tumoral ou de r6cidive, n6cessite d'Stre confirm6 par des 6tudes contr616es. Sa principale limite r6side dans l'absence de validation histo-pathologique des images 6chographiques dans la plupart des 6tudes publi6es.

REFERENCES

1. DE PARADES V. , P A R I S O T C. - - Echographie endo-anale et incontinence f6cale. Ann. Gastroenterol. Hepatol., 1997, 33, 83-7.

2. B A R T R A M C.I . , B U R N E T T S . J . D . - - Atlas of anal endoso- nography. Oxford: Butterworth-Heinemann, 1991.

3. LAW P.J., BARTRAM C.I. - - Anal endosonography : tech- nique and normal anatomy. Gastrointest. Radiol., 1989, 14, 349-53.

4. PALAZZO L., ROSEAU G., VITAUX J., PAOLAGGI J.A. - - Endosonographie du tube digestif. Encycl. Med. Chir. 1995, 9-014-R10, 1-12.

5. GIOVANNINI M., SEITZ J.F., SFEDJ D., ROSELLO R., H O U V E N A E G H E L G., DELPERO J.R., MONGES G., G A U T H I E R A . - - Biopsie dirig6e sous endosonographie endo-vaginale. Diagnostic de r6cidive pelvienne de cancer du canal anal op6r6. A propos de trois observations. Gastroente- rol. Clin. Biol., 1989, 13, 852.

6. GIOVANNINI M., SEITZ J.F., SFEDJ D., HOUVENAE- GHEL G . , D E L P E R O J .R. - - L'endosonographie endo-ano- rectale dans le bilan d'extension et la surveillance des cancers 6pidermoides du canal anal trait6s par radio-chimioth6rapie. Gastroenterol. Clin. Biol. 1992, 16, 994-8.

7. ROSEAU G., PALAZZO L., COLARDELLE P., CHAUS- SADE S., COUTURIER D., PAOLAGGI J.A. - - Endosco- pic ultrasonography in the staging and follow-up of epider- moid carcinoma of the anal canal. Gastrointest. Endosc., 1994, 40, 447-50.

8. GIOVANNINI M., SEITZ J.F., ROSELLO R., HOUVE- NAEGHEL G. , D E L P E R O J .R. , G A U T H I E R A . - - Int6r6t de l'endosonographie endo-ano-rectale dans le bilan d'exten- sion locor6gional et la surveillance des cancers du canal anal. Ann. Gastroenterol. HepatoL, 1990, 26, 3-4.

9. GOLDMAN S., GLIMELIUS B., NORMING U., PAHL- MAN L., S E L I G S O N U . - - Transanorectal ultrasonography in anal carcinoma. A prospective study of patients. Acta Radiol., 1988, 29, 337-41.

10. GOLDMAN S., NORMING U., SVENSSON C., GLIME- LIUS B. - - Transanorectal ultrasonography in the staging of anal epidermoid carcinoma. Int. J. Colorect. Dis., 1991, 6, 152-7.

11. BURTIN P., NAPOLI~ON B. et le Club Franqais d 'Echo- Endoscopic Digestive. - - Standardisation des examens 6cho- endoscopiques en canc6rologie digestive. Gastroenterol Clin Biol 1995; 19: 7-14.

12. WADE D.S., HERRERA L., CASTILLO N.B., PETRELLI N.J. - - Metastases to the lymph nodes in epidermoid carci- noma of the canal anal studied by a clearing technique. Surg. Gynecol? Obstet., 1989, 169, 238-42.

13. NIELSEN M.B., QVITZAU S., PEDERSEN J.F. - - Detec- tion of pericolonic lymph nodes in patients with colorectal can- cer : an in vitro and in vivo study of efficacity of endosonogra- phy. A JR, 1993, 161, 57-60.

14. DETRY R.J., K A R T H E U S E R A.H., L A G N E A U X G., RAHIER J. - - Preoperative lymph node staging in rectal can- cer: a difficult challenge. Int. J. Colorect. Dis., 1996, 11,217-21.

15. GIOVANNINI M., SEITZ J.F., MONGES G., PERRIER H., RABBIA I. - - Fine-needle aspiration cytology guided by endoscopic ultrasonography: results in 141 patients. Endo- scopy, 1995, 27, 171-7.

16. WIERSEMA M.J., KOCHMAN M.L., C R A M E R H.M., TAO L.C., WIERSEMA L . M . - - Endosonography-guided real-time fine-needle aspiration biopsy. Gastrointest Endosc., 1994, 40, 700-7.

17. DEANS G.T., MCALEER J.J.A., SPENCE R.A.J. - - Mali- gnant anal tumours. Br. J. Surg., 1994, 81,500-8.

18. FRAN(~OIS E., P E R O U X J.L., VALLINO P.F., SIMON J .M. , Z E G G A G H A . , G R A N O N C. - - Valeur pronostique de la classification TNM 6cho-endoscopique dans le bilan initial des cancers du canal anal. Gastroent~rol. Clin. Biol., 1996, 20, AllT.

19. GIOVANNINI M., MESSAOUDI S., PERRIER H., HAN- NOUN-LEVY J.M., RESBEUT M., SEITZ J.F, Facteurs pro- nostiques de survie des carcinomes 6pidermofdes du canal anal : r6sultats chez 50 patients. Gastroenterol. Clin. Biol., 1996, 20, A109.

20. FRAN(~OIS E., VALLINO P.F., PEROUX J.L., ZOG- G A G H A., SIMON J.M., GRANON C. - - Le suivi 6cho- endoscopique est-il n6cessaire pour le diagnostic pr6coce de r6cidive de cancer du canal anal ? Gastroent~rol. Clin. BioL, 1996, 20, All8.

Acta Endoscopica Volume 28 - N ~ 4 - 1998 363

21. FINNE CO. - - The role of endorectal sonography in the fol- low-up of malignant disease of the anorectum. Sere. Colon. Rectum. Surg., 1995, 6, 86-93.

22. UKCCCR Anal Cancer Trial Working Party. - - Epidermoid anal cancer: results from the UKCCCR randomised trial of radiotherapy alone versus radiotherapy, 5-fluorouracil, and mitomycin. Lancet, 1996, 348, 1049-54.

23. BARTELINK H., ROELOFSEN F., ESCHWEGE F., ROUGIER P., BOSSET J.F., GONZALEZ GONZALEZ D., PEIFFERT D., VAN GLABBEKE M., PIERART M. - - Concomitant radiotherapy and chimiotherapy is superior to radiotherapy alone in the treatment of locally advanced anal cancer : results of a phase III randomized trial of the European Organization for Research and Treatment of Cancer Radio- therapy and Gastrointestinal Cooperative Groups. J. Clin. Oncol. 1997, 15, 2040-9.

I N T R O D U C T I O N

Endosonography is a new technique and is the first method to provide a satisfactory anatomical image of the anal canal Its use has greatly increased over the last ten years due to the inadequacies of clinical exami- nation, transparietal ultrasound and tomodensitome- try. It is now simple to use, inexpensive, reproducible and free from side-effects.

It is widely used in the study of anal incontinence, for visualizing ruptures o f the sphincter [1] but its potential use in cases of anal tumors has not been extensively studied [2]. However, it may be of great value for helping to determine the choice of therapy for such cases. Here, potential benefits of endosono- graphy in the treatment o f cancer of the anal canal are presented. Its principal limitation is the lack of histo- pathological data to confirm the ultrasound observa- tions, as patients received radiotherapy in most of the published studies.

M A T E R I A L S

The first device to be developed was a rigid probe introduced blindly into the anal canal up to the recto- sigmoid junction. The end of this probe can be covered by a balloon filled with degassed water, producing an acoustic interface between the transducer and the digestive wall allowing study of the rectum. It can also be covered with a plastic hard ultrasound-transparent cone, 10 to 23 mm in diameter and filled with degassed water, for study of the anal canal [3].

The flexible echoendoscope was developed more recently. Its probe, which is between 12 and 17 mm in diameter and covered by a balloon, can be manipula- ted making it possible to direct the ultrasound beam and to go beyond the rectosigmoid. This equipment is more expensive than the rigid probe, and the balloon, because o f its limited compliance, may impede the study of the anal canal [4]. A frequency of 5 to 10 MHz is currently used for examination of the anal canal and the rectum.

M E T H O D S

The ambulatory patient is given an enema and pla- ced in the gynecological position or made to lie on their side. The probe is inserted and images are studied as the probe is gently and gradually withdrawn [3, 4]. Ultrasound investigation can also be carried out via

the vagina, particularly in cases of anal stenosis pre- venting insertion of the probe or after abdominoperi- neal amputation [5]. A sedative is required in a few cases to overcome pain [6, 7].

A transverse ultrasound image of 270 to 360 ~ of the circumference is obtained, perpendicular to the axis of the probe for mechanical and rotating axial probes. A sagittal image, perpendicular to the axis of the equip- ment is obtained with electronic probes [3, 4].

U S E S O F U L T R A S O U N D I M A G E S

1) Positive diagnosis

Anal tumors appear on ultrasound scans as ill-defi- ned, hypo- or hyperechogenic masses of variable tex- ture, located in the wall o f the anal canal, possibly extending into the neighboring organs [6-10]. Howe- ver, the appearance is not specific for a particular condition and endosonography cannot distinguish a malignant tumor (Fig. 1, 2 and 3) from a benign tumor, a lymphoma or an abscess (Fig. 4). Anatomical and pathological analysis is thus required to confirm any diagnosis.

2) Local and regional staging before treatment

T u m o r e x t e n t

Endosonography can be used to determine the loca- tion of the tumor, it size, its height at the circumference and its extension towards the anal sphincter, the vagina, the prostate or the seminal vesicles [6-11]. Endosonography is much more accurate than clinical examination for evaluating the depth of the tumor. In a prospective study o f 50 squamous cell carcinomas, Goldman et al. found that clinical examination failed to detect extension of the tumor beyond the sphincter in 63 % of cases [10].

An ultrasound classification has been developed [6, 10] :

- - UT1 : tumor confined to the mucosa and submu- cosa (Fig. 1),

- - UT2 : tumor limited to the internal sphincter above the puborectum and/or the rectal muscularis propria,

- - UT3 : tumor extending beyond the internal sphincter and/or the rectal muscularis propria (Fig. 2 and 3),

- - UT4 : expansion o f the tumor to an adjacent organ.

364 Volume 28- N ~ 4 - 1998 Acta Endoscopica

Lymph node spread

Normal lymph nodes are often not visible on endo- sonography. They are presumed metastatic i f they have an echogenecity similar to the primary tumor or if they are hypoechoic, round, with well-defined edges, and measure more than 5 to 10 mm. However, true invasive lymph node measuring less than 5 mm cannot be detected. Thus, distinguishing an invasive lymph node (Fig. 5) from a reactionary inflammatory lymph node (Fig. 6) is currently difficult by ultrasound tech- niques [6, 7, 9, 12].

As is the case for rectal tumors, the sensitivity and specificity of the ganglion examination need to be improved [13, 14]. Ultrasound-guided cytological aspi- rations and~or biopsies can be used to confirm the inva- sire nature of a lymph node. This combined approach has ted to greatly improved diagnosis [15, 16].

Consequences for treatment of local and regional examination

The local and regional tumor staging is o f major value in treatment. It makes it possible to design a combined chemotherapy and radiotherapy treatment for patients with large tumors (UT3 or UT4). The detection of para-rectal satellite lymph node can lead not only to the enlargement of the radiation field and the use of chemotherapy in conjunction with radiothe- rapy, it can also prevent unnecessary radium therapy. Controlled studies are required to assess the exact contribution of this technique to therapeutic decisions.

3) Evaluation of prognosis

The value of endosonography for predicting progno- sis was not unexpected as the prognosis for anal can- cers depends partly on the size of the tumor and also whether or not there are metastatic lymph node [17].

Goldman et al. found there was a significant corre- lation (Table 1) between ultrasound tumor staging and the response to treatment [10]. This correlation has also been reported in other studies [6, 18], but has nevertheless been disputed [7, 19]. Franqois et al. sho- wed that there was a significant correlation (Table II) between the detection of lymph node by endosonogra-

TABLE I

C O R R E L A T I O N BETWEEN ULTRASONIC STAGING AND T R E A T M E N T RESPONSE (p < 0,05) [10]

Staging Size (cm) n Complete response (%)

UTI-2 < 5 13 100 UT3-4 < 5 22 64 UT3-4 > 5 11 0

TAB L E II

C O R R E L A T I O N BETWEEN THE ULTRASONIC LYMPH N O D E STAGING AND THE T R E A T M E N T RESPONSE

(p = 0,03) [18]

Staging n Complete response (%)

N - 22 68 N + 13 23

phy and the response to treatment [18]. This relation- ship was confirmed by Giovannini et al. [19].

4) Detection of residual and recurrent tumors

Endosonography can be used after medical treat- ment to determine whether there are any residual tumors or lymph nodes requiring high-dose radio- therapy or abdominoperineal amputation [6, 7, 10].

It can also be used to detect recurrent local tumors after treatment and is much more efficient than tomo- densitometry for thb purpose [6-8, 20]. However, it has not been shown to detect these recurrent tumors earlier than clinical examination [20, 21]. Radiotherapy cur- rently causes tissue changes, particularly edema, necrosis and fibrosis. Some of these changes such as thickening o f the rectal wall, predominantly in the muscularis propria (Fig. 7) or hypo- or hyperechoge- nic patches in the rectal wall or peri-rectal area, may have the same appearance as recurrence in ultrasound images (Fig. 8 and 9). However, an increase in size bet- ween two successive examinations is strong evidence for a developing tumor. In this case, ultrasound-gui- ded aspiration is' essential for decision-making as it can confirm the diagnosis of a recurrence: confirming this diagnosis is necessary before deciding to treat the patient with high-dose radiotherapy or by abdomino- perineal amputation [5-7, 20, 21].

In practice, most authors recommend carrying out control endosonography checks every three or four months, at least for the first two years following treat- ment for rectal tumors.

CONCLUSION

Endosonography is an effective tool, more reliable than clinical examination and tomodensitometry, with many applications in the pathology of anal tumors. It can be used effectively for examining tumor extent and lymph node spread. It is very important beacause two recent randomised trials have shown that conco- mitant radiotherapy and chemotherapy is superior to radiotherapy alone in T3-4 NO-3 or T1-2 N1-3 anal cancer with improvement in locoregional control, colostomy-free interval and local recurrence rate [22, 23]. It can assess prognosis and detect residual or recurrent tumors after treatment. Echo-guided cytolo- gical aspiration and biopsy can be used to confirm the invasive nature of lymph nodes and recurrent tumors. However, controlled studies are still required to confirm the value of endosonography in determining treatment and choosing adjuvant chemotherapy for large tumors and~or suspected metastatic lymph node, high-dose radiotherapy or abdominoperineal ampu- tation in cases of" residual or recurrent tumors, pre- venting unnecessary radium therapy in case of suspec- ted metastatic lymph node. Currently, the principal limitation to the use of this technique is the lack of his- topathological validation for ultrasound images in most published studies.

Acta Endoscopica V o l u m e 2 8 - N ~ 4 - 1998 365