Carcinoembryonic antigen (CEA) in gastrointestinal and extragastrointestinal tumors and its relationship to tumor‐cell differentiation

Abstract

Abstract Carcinomas of gastrointestinal (colon, stomach, pancreas, liver) and of extragastrointestinal (bronchus, breast, tonsil, anus, ovary) origin and normal large‐bowel mucosa were studied by indirect immunofluorescence for the presence of the carcinoembryonic antigen (CEA). In addition, an attempt was made to correlate the CEA content of the tumors with the degree of their cellular differentiation. In well‐differentiated tumors of the colon, including hypersecretory well‐differentiated mucoid carcinomas, CEA was abundant on the luminal tumor cell surface and in the lumina of the glands. In moderately differentiated ones, CEA was present in rather low concentrations on the luminal surface and in secondary glandular structures. In poorly differentiated anaplastic carcinomas, CEA was absent. In non‐cancerous colonic mucosa surrounding the tumor, in colonic mucosa distant from the tumor as well as in colonic mucosa taken at autopsy from subjects with non‐neoplastic extragastrointestinal diseases, CEA could not be found by indirect immunofluorescence. The CEA content of gastric carcinomas was lower than in colonic tumors, although the distribution was similar. In pancreatic cancers, CEA was present in variable amounts depending upon the differentiation of the individual tumor. In these malignancies, CEA was found not only on the luminal surface and in the lumina, but also in the cytoplasm of isolated tumor cells. CEA was not detected in carcinomas of extragastrointestinal origin by indirect immunofluorescence. The localization of CEA on the surface (probably glycocalyx) of the cell, together with its dependence upon a certain degree of tumor cell differentiation, suggest that CEA is a secretion product rather than a constituent of the tumor cell membrane.