The presence of anti-carcinoembryonic antigen (CEA) antibodies in the sera of patients with gastrointestinal malignancies.

Using an enzyme-linked immunoassay we tested the sera of 71 patients with digestive system cancer, 35 patients with various nonmalignant disorders, and 28 normal individuals for anti-CEA activity. Antibodies were found in the sera of 51% of the patients. Most of the patients positive for the antibodies (70%) had no evidence of metastatic disease. Fewer than 10% of the sera from control groups had anti-CEA activity. The authors concluded that the patients suffering from cancer of the GI system are capable of producing tumor-specific antibodies. These antibodies could be used as a tumor marker and/or as a possible index for the function of the immune system. The presence of a large tumor mass could lead to the removal of these antibodies from the circulation.