Carcino Embryonic Antigen (CEA) is synthesised during development in the fetal gut, and is re-expressed in increased amounts in intestinal carcinomas and several other tumors. Antibodies to CEA are useful in identifying the origin of various metastatic adenocarcinomas and in distinguishing pulmonary adenocarcinomas (60 to 70% are CEA+) from pleural mesotheliomas (rarely or weakly CEA+). The carcinoembryonic antigen (CEA) is a member of a large family of glycoproteins and a useful tumor marker for adenocarcinoma. Tissue specificity: Found in adenocarcinomas of endodermally derived digestive system epithelium and fetal colon.