Absence of circulating antibodies to carcinoembryonic antigen in patients with gastrointestinal malignancies

The zirconyl phosphate gel assay (Z‐gel) was used to assay sera of 265 patients for humoral activity against carcinoembryonic antigen (CEA). Included in the patients tested were 110 with non‐metastatic colon carcinoma, 122 with other gastrointestinal, breast and pulmonary neoplasms, 20 pregnant women and 13 healthy volunteers. Twenty‐five of the patients were also analyzed with molecular filtration column chromatography. Antibody activity directed against CEA could not be detected with either technique. Possible explanations for these results are discussed.