Antigenic heterogeneity and individuality in adenocarcinomas of the rectum and their secondaries

The reaction patterns of eight antibodies directed against blood group substances A, B and H, respectively, against Lewis B antigen, difucosylated carbohydrate antigens (DFCA), gastrointestinal cancer antigen CA 19-9 (GICA), carcinoma-associated antigen CA-50 and CEA, were studied in 68 rectal carcinomas using the avidin-biotin-peroxidase method. A pronounced intratumoral antigenic heterogeneity was revealed for most antigens. It thus became evident that an interpretation based upon small preoperative biopsies would be inaccurate. The overall proportion of positive carcinoma cells, however, did not vary much between larger samples taken postoperatively from different regions of the tumours. The intertumoral antigenic variability was also considerable: nearly all tumours had an individual immunohistochemical profile according to the proportions of positive cells. Heterogeneous staining patterns were also present within metastases, and lymph node metastases from the primary tumour in some cases differed completely from each other. The staining pattern did not correlate with Dukes' stage, and degree of differentiation; the expression of any individual antigen, or several antigens in combination.