Expression of carbohydrate antigen 19-9 and stage-specific embryonic antigen 1 in nontumorous and tumorous epithelia of the human colon and rectum.

The expression of carbohydrate antigen 19-9 (CA 19-9) and stage-specific embryonic antigen 1 (SSEA-1) in various human colorectal epithelia was examined by an immunohistochemical method. In mucosa remote from the carcinoma, CA 19-9 was not expressed, whereas SSEA-1 was only faintly expressed in lower crypts in all cases. In mucosa adjacent to the carcinoma, CA 19-9 was weakly expressed in upper crypts in 20% of the cases, whereas SSEA-1 was expressed not only in lower crypts in all cases but also in upper crypts in 93.3% of the cases. In adenoma, CA 19-9 was expressed in 80.6% of the cases, and SSEA-1 was expressed in all cases. The expression of both antigens was to some extent related to the degree of cellular atypia. In focal carcinoma in adenoma, CA 19-9 was strongly and diffusely expressed in 50% of the cases, and SSEA-1 was strongly and diffusely expressed in all cases. In advanced carcinoma, CA 19-9 was homogeneously or heterogeneously expressed in 82.2% of the cases, and SSEA-1 was homogeneously or heterogeneously expressed in all cases, but lower intensity of SSEA-1 staining was associated with a decrease in the degree of carcinoma differentiation. These results show that the expression of both CA 19-9 and SSEA-1 changes along with neoplastic transformation and progression in the colon and rectum. Immunohistochemical studies of SSEA-1 in flat colorectal mucosa might be a useful approach for detecting foci with preneoplastic change in the general population, whereas those of SSEA-1 and CA 19-9 could be a useful method for detecting focal carcinoma in adenoma.