Carcinoembryonic antigen estimation in nipple discharge as an adjunctive tool in the diagnosis of early breast cancer.

To assess the usefulness of carcinoembryonic antigen (CEA) estimation in nipple discharge for the detection of nonpalpable breast cancer, CEA activity in nipple discharge was measured by enzyme immunoassay using monoclonal antibody. The specificity of the antibody for breast cancer was assessed by an immunohistochemical method. Mean CEA levels in the nipple discharge from 18 patients with benign breast diseases (ten intraductal papilloma; eight fibrocystic disease) was 43 ng/ml (SD, 34 ng/ml), suggesting an upper reference limit of 100 ng/ml. Six of seven nonpalpable breast cancer patients had higher CEA levels than this tentative cutoff value, as did three of five patients with borderline lesions. The incidence of elevated CEA levels in nipple discharge correlated significantly with the incidence of intratumoral antigen expression. These results lead us to conclude that CEA measurement in nipple discharge may be a useful adjunct in the diagnosis of nonpalpable breast cancer.