[The carcinoembryonic antigen: apropos of an old friend].

The carcinoembryonic antigen (CEA) is glycoprotein localized in the apical surface of mature enterocytes. The members of the CEA gene family are clustered on chromosome 19q13.2. It is formed by 29 genes, of which 18 are expressed. Many functions of CEA have been known in healthy indiuiduals, however its role as cell adhesion molecule is the most studied. Besides the colon, CEA is expressed in the stomach, tongue, oesophagus, cervix, and prostate. The most important clinical function is in colorectal, gastric and ovary cancer. It is used as prognosis marker, staging system, recurrence, treatment response and liver metastases. There are many non-neoplasic diseases that enhance CEA value. Actually, CEA is being studying as target of immunotherapy.