Esophageal carcinoma : Clinical TNM staging with endosonography and computed tomography

The prognosis of esophageal carcinoma has remained poor 
despite improvement of diagnostic modalities. Endosonography and computed 
tomography were performed for preoperative TNM staging (clinical TNM) of 
esophageal carcinoma. Endosonography was superior to computed tomography 
for diagnosing early stages and nonresectability of carcinoma. Endosonography 
was also superior to computed tomography in diagnosing regional lymph node 
metastases. For diagnosing nonmetastatic lymph nodes, however, computed 
tomography was superior. Endosonography was superior for diagnosing celiac 
lymph node metastases but less accurate in detecting liver involvement. Endosonography 
was accurate for clinical TNM staging of esophageal carcinoma. 
The possibility of performing cytology and biopsy will further enhance the 
diagnostic value of endosonography.

Le role de l'endosonographie dans le cancer de l'oesophage: La classification TNM clinique RESUME: Le pronostic du cancer de l'oesophage reste mauvais malgre l'amelioration des modalites diagnostiques.L'endosonograph ie et la tomographie assistfr par ordinateur ont ete effectuees pour la classification pTNM (TNM clinique) des cancers de l'oesophage.L'endosonographie s'est averee superieure a la tomographic assistee par ordinateur clans le d iagnostic des cancers aux stades precoces el de la no n-resecabilite des tumeurs.L'endosonographie etaic egalement superie ure a la tomographic assistee parordinateur pour diagnostiquer Academic Medical Cemer.Department of Gastroenterology-He/mwlogy, Amsterdam.The Netherl.ands Correspondence and reprints: Dr TL Tio, Academic Medical Center, Department of Gastroenterology-Hepawlogy , Meibergdreef9 , I 105 AZ Amsterdam, The Necherl.aruk Telephone 020 -566 9 I 11 , Fax 020 -566 4440 CAN J GASTROENTEROL VOL 4 No 9 DECEMHER 1990 E SOPI IACiEAL CARCINOMA IS USU- al I y diagnosed in late stages.The prognosis of adva nced carcino ma is poor.Early stages of lhe disease are incidentally found in the evaluation of patients with dysphagia.Early esophageal carcinoma is defined as carcinoma localized in the mucosa or submucosa with no evidence of lymph node involvement.A large series nf patients with ea rl y esophageal cance r was reported in C hina and Japan ( 1-5 ).TNM classification ha~ been widely used for staging esophageal carcinoma (6-8).The depth of tumour infiltration is used as the crite rion for staging tumour categories.The defini tion of regional lymph nodes has been modified and lymph node classification si mplified.Computed tomog rap h y is widely used for staging esophageal carcinomas.The accuracy of computed tomography, however, is variable (9,10).

INTERPRETATION OF ENDOSONOGRAPHIC IMAGES
Sonographic interpretation of gastrointestinal wall suuct ure and perigastrointestinal lymph no<les is based on results obtained through detailed examination of resected specimens and autqisy materials.In essence, endosonography visualizes a five layer structure, which shows close corrdation with wall histology.An esophageal carcinoma is imaged as a hypoechoic echo pattern with partial or total destruction of the normal architecture.Endosonography criteria for assessment of the depth of tumour infiltration are summarized in Table 2.

TABLE 2
Cnteria for assessing lymph node metastases are as follows: Lymph nodes with hypoechoic patterns and clearly delineated bnund,1ries are suspicious of malignancy.Direct extension of mural ahnormalities into adjacen t lymph nodes is highly suspicious of malignancy (pathognomon1c).Lymph nodes with hyperechoic (echogenic) patterns and indistinctly demarcated boundaries are indicative of benignancy.

COMPUTED TOMOGRAPHY IMAGES
For computed tomography staging pTI and pT2 are grouped together because computed tomography is not able to image the muscularis propria (Tahle 3 ).Thus, distinct inn between these two groups is not possihle.

COMPARISON BETWEEN ENDOSONOGRAPHY, COMPUTED TOMOGRAPHY AND HISTOLOGY
Recently, a prospective study was performed with en<losonography and computed tomography in 74 patients with esophageal carcinoma (20).The resul ts of this preoperative study were correlmed with the histology of rcsected specimens according to the new ( 1987) TNM classification.
In another study with a more ex tensive series of patients (n=9 l) the ace u ra cy of encloso nogrnph y in diagnosing Tl carc inomas was 82%, T2 c;ucinomas 85%, T 3 carcino mas 94% and T4 carcinomas 92%.Overscaging occ urred 1n 6''.{, a nd understaging in 4% wall ( c) ad1acem w the aorta wllh a f eedmg wbe (f) m the esof1hagu..~ (21).The results of staging regional lymph nodes and distant metastas is were comparable to those of the previous study.

CONCLUSIONS
Endosonography is more acLuratc than computed tomography in the preoperative TNM c lass ifica tt n n o t esophageal c.arci noma.l lowever, inadequate examinatio n of e nJosonngraphy can occ.ur in the presen ce o f severe stenos is.Suc h obstructi ve tumours <lo not limit the role o f computed tomography scanning.The recently available cathete r echoprohe is prom1s mg for the staging of severe obstructed esophageal carc inoma.Moreover, endosonography stag mg can be 6.Endosonography 1s accurate for~t.1g•ing esophagea l carcinomas inJcpcn, dent of their loca l 1zation Computed tomography ts not as rcliahlc for staging Larcinoma at tht• esnphagocarJial 1110 uon as for staging esophage;i I ca rc1rurn The mutme U':,C tf cndosonography-gwJ.I cytok)!..ry for tissue Jiagi1os1s, part1cul 111 lymph node metastasis, will further en, h a nce the J1a g nos t1c va lue of cnclosonography.

Technical data of the Olympus echoendoscopes used for clinical TNM staging of esophageal carcinoma
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