Tissue concentrations of CEA and CA 19-9 in the carcinogenesis of colorectal carcinoma exemplified by the adenoma-carcinoma sequence

To study the behavior of the tumor-associated antigens CEA and CA 19-9 in colorectal carcinogenesis, exemplified by the adenoma-carcinoma sequence, their tissue concentrations were measured in adenomas of different size and histology and compared with those found in normal colonic mucosa and carcinoma. Both in the case of monoclonal and polyclonal CEA assay, significantly higher concentrations were found in the adenoma tissue as compared with normal mucosa. Carcinomas revealed, on average, an even higher tissue CEA level, but the concentrations measured showed considerable scatter. In the adenoma group, the villous lesions and those with severe cellular atypia were characterized by markedly higher CEA concentrations, reflecting their special position in the adenoma-carcinoma sequence. In the case of CA 19-9, too, an increase in tissue concentrations from normal mucosa through adenoma to carcinoma was observed. In contrast, among the adenomas of different histologies and dysplasia no differences were observed. These findings fit with the concept of the adenoma-carcinoma sequence which, in our opinion, represents a suitable model for studying the significance of tumor-associated antigens in the carcinogenesis of colorectal cancer and its precursors.