Carcinoembryonic antigen in breast nipple aspirate fluid.

New diagnostic tools are needed to complement mammography and physical examinations for early detection of breast cancer, particularly among younger women. We evaluated the tumor biomarker, carcinoembryonic antigen (CEA), in 215 nipple aspirate fluid (NAF) samples collected from one or both breasts of 147 women, ages 27-87 years. Most subjects were recruited at the time of mammography examination. The 215 nipple fluid CEAs range from undetectable levels to 8400 ng/ml (median, 1100 ng/ml). Normal serum CEA levels are less than 6 ng/ml. There are no significant differences between the CEAs in fluid from normal breasts (112 samples) and breasts with various histories of tumors (total, 103 samples). Analyses for determinants of CEAs in fluids from normal breasts show higher levels among current smokers (P = 0.03) and marginal elevations among nulliparous women (P = 0.07). CEAs in these samples are not correlated with age, menopausal status, current hormone use, prior breastfeeding, or family history of breast cancer. Follow-up studies of these women and comparisons of CEAs in fluids from normal and cancer-containing breasts will help clarify whether this biomarker is useful for risk assessment or early cancer detection.