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

OBJECTIVE: The discovery of antibodies against carcinoembryonic antigen (CEA) in patients with digestive cancers, in the late 1970s, initiated a number of studies on the role of these antibodies in patients with cancers of the GI tract. Our aim was to determine the prevalence and prognostic significance of the IgG and IgM anti-CEA antibodies in the serum of patients with colon cancer. METHODS: Using an enzyme-linked immunoassay, the sera of 58 colon cancer patients 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 IgM anti-CEA antibodies. RESULTS: The CEA was elevated (greater than or equal to 10 ng/ml) in only 12 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 the 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 compared to the rest of the patients (p = 0.017). The IgM anti-CEA antibodies can 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 circulating anti-CEA antibodies in their sera. These may be used as diagnostic markers and as independent prognostic factors. In addition, the presence of these antibodies in the patients studied is associated with better prognosis and significantly increased 2-yr survival. It was also found that the anti-CEA antibodies (IgG and IgM) are more sensitive markers than CEA. These findings underline the biological importance of the anti-CEA antibodies and provide additional information on their potential use as markers of the immune status in patients with colon cancer. (C) 2000 by Am. Cell. of Gastroenterology.