Comparative study for histology, proliferative activity, glycoproteins, and p53 protein between old and recent colorectal adenomas in Japan

The incidence of colorectal carcinoma is increasing in Japan. Malignant tra nsformation in colorectal. neoplasia is usually considered to be owing to a denoma-carcinoma sequence. Elucidation of the recent alteration in the biol ogical properties of colorectal adenoma is sure to be useful to understand the recent increase of the colorectal carcinoma in Japan. We compared the h istopathological feature, mitotic index, proliferative activity (Ki-67 labe ling index), expression of glycoproteins such as MUC2 mucin, sialyl Lewis A (SLe(a)) and sialyl dimeric Lewis X (SLe(x)), and p53 protein overexpressi on, between 108 adenomas in the old period (Group A, from 1969 to 1985) and 140 adenomas in the recent period (Group B, from 1995 to 1998). The histol ogical dysplasia, mitotic index and Ki-67 labeling index of the adenomas we re significantly higher in Group B than in Group A. In contrast, the expres sion of MUC2 mucin, which is considered to be a differentiation factor of i ntestinal mucosal epthelium, was significantly reduced in Group B than in G roup A. The SLe(a) and SLe(x) expressions showed no significant difference between them. The p53 expression showed no significant difference between t hem, except for the moderate dysplasia. These findings indicate that recent colorectal adenomas show more advanced degrees of histological dysplasia, more rapid growth, and reduced differentiation than colorectal adenomas, wh ich developed at earlier times, and may be related with the recent high inc idence of colorectal. carcinoma in Japan. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.