[Prolactin and breast cancers].

Prolactin has a cocarcinogenic activity in the rat and mouse as its administration or stimulation of endogenous secretion increases the incidence and reduces the latent period of breast tumours, whether spontaneous or induced by chemical carcinogens. Prolonged hyperprolactinemia obtained by neutralizing the inhibitory influence of the hypothalamus on its secretion and liberation, favours the development of breast carcinoma and inversely. (Estrogens and prolactin exert a synergistic effect, both centrally and peripherally, on the acinar cells of the breast. Prolactin dependency of these mammary carcinomas is due to the persistence of specific cell receptors. In human pathology, it has not yet been possible to demonstrate a comparable effect of prolactin. Radioimmunoassay of plasma prolactin and specific receptors, together with epidemiological enquiries, should rapidly confirm or refute the cocarcinogenic effect of prolactin.