Old friend carcinoembryonic antigen (CEA) was the topic of a recent consensus development conference at the National Institutes of Health in Bethesda, Md. The reason? Although the tumor marker has been known and studied for about 15 years, its role in the diagnosis and management of cancer remains uncertain.
A glycoprotein of 150,000 to 200,000 molecular weight, CEA was first detected in 1965 in the sera of patients with adenocarcinoma of the colon, the result of a directed search by Phil Gold, MD, and co-workers at McGill University, Montreal, for a tumor marker. Subsequent investigations demonstrated that the antigen was present not only in malignant tumors arising from entodermally derived digestive tissues but also in the embryonic and fetal gut, pancreas, and liver during the first two trimesters of gestation. Thus, it was named carcinoembryonic antigen.
Through the years, however, the sensitivity of the assays used to detect CEA has