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.