Immunohistologic study of blood group substances in polyps of the distal colon. Expression of a fetal antigen.

Forty-four polyps and 14 adenocarcinomas of the left colon from 28 patients were studied for the presence of blood group substances of the A, B system, using the method of specific erythrocytic adherence. Forty-one percent of all polyps and 57% of all cancers were found to have reactivity for blood group substances. Fifty-four percent of villous adenomas (seven of 13), 39% of tubular adenomas (five of 13), 14% of mixed tubulovillous adenomas (one of seven), and no hyperplastic polyps (zero of four) showed reactivity for blood group substances. Lesional blood group substance reactivity, when present, was the same as that for the patient's own blood group type, with the exception of two patients of B blood group type, whose lesions had A-blood group substance reactivity. Cytologic atypia showed no correlation with the presence of blood group substances. Polyps with blood group substance reactivity were seen more frequently in patients with cancer. Twelve patients had both a cancer and a polyp studied, with both polyp and cancer showing similar blood group substance reactivity for nine of these patients. A, B, H-blood group substances in the left colon are normally absent in the adult and present only in the fetus. The reappearance of these fetal antigens in both polyps and cancers adds immunologic evidence to the theory that colonic adenocarcinoma evolves through a polyp-cancer sequence.