ABSTRACT
The prime importance of estrogens and prolactin (PRL) in murine species has been established with such clarity that it was reasonable to expect a similar relationship between these hormones and breast disease in man. Of immediate relevance is the role that PRL plays in mammary gland function. The classical experiment of W. R. Lyons showed clearly that PRL was essential for complete lobularalveolar development of the mammary gland. The isolation of pure human PRL led to the rapid establishment of a radioimmunoassay and in the decade after the discovery of the hormone much basic physiological research was carried out to investigate the biological role of PRL in women. Women with a family history of breast cancer have a greater than twofold excess risk of breast cancer, providing their mother’s or sister’s disease occurs premenopausally. Premenopausal PRL levels have been reported to be higher in women with a family history of breast cancer.
