CEA determination in the follow-up of extracolorectal neoplasms.

CEA was initially described as a tumor and organ specific colorectal antigen, but later found by more sensitive methods in other tumors (stomach, pancreas, lung, breast) and in minor amounts in inflammatory, normal adult and fetal organs of the gastrointestinal tract. The main clinical application of CEA concerns its pretherapeutic and serial determination as circulating antigen in serum and other body fluids by means of CEA-specific, commercially available test kits. By clinical studies a significant correlation has been proven between the pretherapeutic serum CEA level and tumor stages and prognosis. Moreover, serial CEA level changes have been shown a valuable monitor following operation or during radio/chemotherapy anticipating and reflecting the clinical course of disease. In combination with newly established tumor markers, the main clinical indication for CEA determination in addition to colorectal cancer concerns monitoring of patients with stomach (+CA 72-4), lung (+NSE/SCC) and breast cancer (+CA 15-3/MCA).