Carcinoembryonic-like substance in breast fluid discharge in benign and malignant breast disease and in milk of lactating women.

In a search for a simple noninvasive test for early detection of breast cancer, radioimmunoassay was used to determine carcinoembryonic (CEA) levels in the serum and breast fluid of 26 women presenting with spontaneous breast discharge, and in the serum and milk of 34 postpartum lactating women. In 54 milk samples from 34 healthy nursing mothers, the mean CEA level was 62.6 +/- 49.2 ng/ml (mean +/- SD) (range 5 to 252 ng/ml). The highest levels were found during the first days after delivery. Serum CEA levels measured in 18 of the 34 mothers were negative in 12 cases and normal (10 +/- 5.3 ng/ml) in six. No correlation was found between CEA levels in milk and those in serum. In the women with spontaneous breast fluid discharge, CEA levels in the breast fluid measured less than 300 ng/ml in 10 cases, 300 to 1,000 ng/ml in 9 cases and greater than 1,000 ng/ml in 7 cases. None of the 19 women with CEA values below 1,000 ng/ml had a malignancy. Four of the seven women with the highest CEA levels were found to have breast cancer. Serum CEA levels were within the normal range in both the malignant and nonmalignant cases. We conclude that CEA levels are markedly elevated in breast fluid discharges in nonlactating women, and that the highest levels may be associated with malignancy.