The adenoma-carcinoma sequence in rectal adenomas: support by the expression of blood group substances and carcinoma antigens

The reaction patterns of eight antibodies directed against blood group substances A, B, and H and against Lewis B antigen, difucosylated carbohydrate antigens (DFCA), gastrointestinal cancer antigen (GICA) CA 19-9, carcinoma-associated antigen CA-50, and carcinoembryonic antigen (CEA) were studied in mucosa and adenomas of the rectum. Antigenic heterogeneity was a common feature of rectal mucosa and was observed to a considerable degree in adenomas. In general, the rectal mucosa expressed only a few antigens and to a limited extent. The adenomas were more extensively stained than the rectal mucosa. The proportion of positive cells increased with the grade of dysplasia but was relatively unrelated to the histologic type. The proportion of individual antigens expressed and the number of antigens extensively expressed increased between rectal mucosa, benign adenomas, and adenomas with early invasive carcinoma. These findings support the concept of an adenoma (dysplasia)-carcinoma sequence.