Abstract

Several reports have indicated that the breast fluid obtained by nipple aspiration provides valuable biological material for inclusion in studies of breast cancer biochemical epidemiology. Breast fluids contain a variety of hormones and growth factors, often at concentrations considerably higher than those in the corresponding serum. Aspirates from benign breast disease patients have very high levels of bioactive lactogenic hormones and, to a lesser extent, immunoassayable prolactin, compared with healthy controls. A growth hormone-like protein, recognized in a radioimmunoassay but not in a growth hormone-specific immunoradiometric assay, and lacking activity in the Nb2 cell bioassay, is usually present in fluids from Finnish (low breast cancer risk) but not American (high breast cancer risk) women. Epidermal growth factor and transforming growth factor-alpha are present in breast fluids, with preliminary indications that these functionally related polypeptides occur at relatively high concentrations in benign breast disease.