Best marker to assess prognosis after Surgery for colon carcinoma:

CEA is a family of related glycoproteins initially found in embryonic tissue and colon malignancies. The half-life of CEA is approximately 2 weeks. Plasma levels of CEA can be determined readily by radioimmunoassay. However, its usefulness in colon carcinogenesis screening is limited because of its high level in the plasma of a patient&;s malignancies originating from other sites such as breast, pancreas, stomach and lung. Fuhermore, CEA plasma levels may also be increased in smokers or patients with chronic diseases, such as inflammatory bowel disease, bronchitis and alcoholic liver disease. The clinical usefulness of CEA for screening purposes is fuher limited by the fact that its increase in level typically occurs only when the tumor penetrates through the serosa. Thus, early lesions may not be detected by serum CEA level changes. CEA is typically elevated with metastatic liver disease, but rarely with peritoneal involvement. Thus, while the specificity for CEA to identify occult CRCs is high, the sensitivity is low in most studies for screening. Accordingly, CEA is not a useful test for the screening of CRC. Ref : Bailey and love surgery text book 27th Ed.