HISTOPATHOLOGICAL STUDIES OF SUPERFICIAL-TYPE EARLY COLORECTAL-CARCINOMA

BACKGROUND. Superficial-type early colorectal carcinoma. (SCa) is pres ently not a rare finding and is very important in discussions regardin g the development of large bowel cancers, although the histologic char acteristics of SCa remain obscure. METHODS. Using 54 SCa lesions (34 i ntramucosal adenocarcinomas (SCa-m) and 20 adenocarcinomas with invasi on to the submucosa (SCa-sm)), the largest dimension of the depressed region of the lesion and the greatest dimension of the entire lesion w ere measured by the computed image analyzer, and the expression of p53 and ras of SCa were examined im immunohistochemically. RESULTS. The p ercent of depressed regions in SCa lesions measuring less than 5 mm in greatest extent was larger than in those measuring more than 6 mm, an d the percent of depressed regions in SCa-sm with deeper carcinoma inv asion was lower than that of SCa-sm with shallower invasion. There was a positive correlation between the depth of invasion and the maximum dimension of the carcinoma. The frequency of association with adenoma in all SCa-m was 21% and was 32% in SCa-m that were more than 6 mm in greatest extent, although all minute SCa-m lesions less than 5 mm were pure carcinomas without any adenomatous component. Positive expressio n of ras was noted in 41% of SCa-m and 36% of SCa-sm, respectively, wh ile positive expression of p53 was noted in 63% of SCa-m and 88% of SC a-sm, respectively. CONCLUSIONS. These results suggested that 70% to 8 0% of SCa developed via a de novo carcinoma theory and showed the depr ession form in the initial histologic stage and thereafter in the flat -protrusion form, while 20% to 30% of SCa arose from the preexisting f lat adenoma via the adenoma-carcinoma sequence theory. The results als o suggested that p53 was related to the enlargement and deeper invasio n of SCa, regardless of the sequence of development of colorectal canc er. (C) 1996 American Cancer Society.