[Prolactin and breast cancer].

In the animal, prolactin favours growth of breast tumours. Prolonged hyperprolactinemia occurring after the action of a carcinogenic agent increases the incidence of these tumours, but hyperprolactinemia, induced before the application of such an agent, reduces it. In women, there is also evidence in favour of the influence of prolactin on growth and on the incidence of breast carcinomas, but this evidence is still very indirect and sometimes contradictory. Serum levels of prolactin in women with carcinoma of the breast are identical to those observed in a female population of comparable age. In cases of generalised carcinoma, hysterectomy and ovariectomy induce remissions. These operations should be followed by a fall in prolactinemia. They also reduce the incidence of carcinoma of the breast in women. A full term pregnancy before the age of thirty years, apparently protects the mammary gland from the etiological agent. Now, in women, the secretion of prolactin is considerably increased during pregnancy.