An evaluation of the clinical usefulness of CEA in colorectal cancer.

Carcinoembryonic antigen is the most common tumor marker in use today. Plasma CEA has no role as a screening tool for large patient populations but does correlate with tumor stage, prognosis, and extent of surgical resection for individual patients. Serial monitoring of plasma CEA levels can detect tumor recurrence prior to clinical or radiologic evidence of disease. An elevated or progressively rising post-operative CEA level is a definite indication for surgical reexploration, with the intent to surgically resect locally recurrent or metastatic disease. Finally, anti-CEA antibodies may be used in the future to improve preoperative staging and to treat colorectal carcinoma.