INVASION DEPTH DIAGNOSIS OF DEPRESSED TYPE EARLY COLORECTAL CANCERS BY COMBINED USE OF VIDEOENDOSCOPY AND CHROMOENDOSCOPY

Background: Depressed type early colorectal cancers are found less fre quently than other polypoid cancers although they have a higher submuc osal invasion rate. Recently videocolonoscopy and chromoendoscopy have become available and precise descriptions of these lesions are now ro utine. Because endoscopic mucosal resection is designated for intramuc osal and focally extended submucosal (m-sm1) cancers, an evaluation of the characteristic findings indicating invasion depth with these moda lities is important. Methods: Between January 1991 and March 1996, 64 depressed type early colorectal cancers were detected and treated. Whe n a faint abnormality of the mucosa was suspected by routine videocolo noscopy, 0.1% of indigo carmine solution was sprayed on the mucosal su rface (chromoendoscopy). Colonoscopic findings of m-sm1 cancers and mo derately and massively extended submucosal (sm2-3) cancers were retros pectively reviewed and compared with confirmed histologic findings. Re sults: Characteristic colonoscopic findings needed for surgical operat ion were as follows: (1) expansion appearance, (2) deep depression sur face, (3) irregular bottom of depression surface, and (4) folds conver ging toward the tumor. By using these findings, the invasion depth of depressed type early colorectal cancers could be correctly determined in 58 of 64 lesions (91%). Conclusions: Characteristic colonoscopic fi ndings obtained by a combination of videocolonoscopy and chromoendosco py are useful for determination of the invasion depth of depressed typ e colorectal cancers, an essential factor in choosing a treatment moda lity.