Prognostic significance of circulating antibodies against carcinoembryonicantigen (anti-CEA) in patients with colon cancer

OBJECTIVE: The discovery of antibodies against carcinoembryonic antigen (CE A) in patients with digestive cancers, in the late 1970s, initiated a numbe r of studies on the role of these antibodies in patients with cancers of th e GI tract. Our aim was to determine the prevalence and prognostic signific ance of the IgG and IgM anti-CEA antibodies in the serum of patients with c olon cancer. METHODS: Using an enzyme-linked immunoassay, the sera of 58 colon cancer pa tients were examined for the presence of carcinoembryonic antigen (CEA) and for circulating antibodies against the CEA (anti-CEA). An inhibition assay was carried out for the determination of the specificity of the IgG and Ig M anti-CEA antibodies. RESULTS: The CEA was elevated (greater than or equal to 10 ng/ml) in only 1 2 patients (20.6%). Anti-CEA IgM and/or IgG antibodies were detected in 46 patients with colon cancer (79.1%). In the control group (n = 28), 10% of t he individuals had detectable amounts of IgG and/or IgM anti-CEA antibodies . Patients with detectable amounts of circulating IgM anti-CEA antibodies ( n = 14, 30.5%) had a statistically significantly better 2-yr survival compa red to the rest of the patients (p = 0.017). The IgM anti-CEA antibodies ca n also be used as an independent prognostic factor in these patients (p = 0 .0323). CONCLUSIONS: In this study, a high number of colon cancer patients have cir culating anti-CEA antibodies in their sera. These may be used as diagnostic markers and as independent prognostic factors. In addition, the presence o f these antibodies in the patients studied is associated with better progno sis and significantly increased 2-yr survival. It was also found that the a nti-CEA antibodies (IgG and IgM) are more sensitive markers than CEA. These findings underline the biological importance of the anti-CEA antibodies an d provide additional information on their potential use as markers of the i mmune status in patients with colon cancer. (C) 2000 by Am. Cell. of Gastro enterology.