Immunohistological study of precancerous mucus modification in human distal colonic polyps.

The M1 antigens associated with gastric fucomucins, oncofetal markers of the distal colonic mucosa, were demonstrated to be more closely associated with adenomas [92 of 139 (66%)] than with invasive adenocarcinomas [27 of 218 (12%)]. They were always expressed in tumors containing the M3 antigen normally associated with the intestinal mucus. The M1 antigens, present in 100% of hyperplastic polyps (30 of 30), were not specific for a particular histological type of adenoma but were found to be more closely associated with those showing a villous differentiation [41 of 47 (87%)] than with those having a tubular pattern [51 of 92 (55%)]. The presence of these M1 antigens depended neither on the size nor on the degree of cytological atypia of the nodular adenomas. However, M1 antigens were found in 94% of the adenomas (35 of 37) concomitant with adenocarcinomas; in contrast, only 56% of adenomas (55 of 102) observed on noncancerous mucosa contained these M1 antigens. As already demonstrated during rat colonic carcinogenesis, mucus modification characterized by the presence of M1 antigens could represent early molecular changes occurring before malignant transformation related to a chemical carcinogen. These M1 antigens might be regarded as early precancerous markers of an oncofetal type, associated with human distal colonic mucosa.