Prolactin and Breast Cancer

Abstract

Prolactin, a peptide hormone with a molecular weight of about 23,000, is secreted by the lactotropic cells of the pituitary gland. The best-known physiologic function of the hormone relates to lactation. The plasma level of prolactin rises during pregnancy. After parturition, prolactin promotes and maintains lactation. Whether prolactin or other pituitary factors have a role in the normal or neoplastic growth of human breast tissue has been controversial.In this issue of the Journal, Musey et al. report that pregnancy has a subsequent, long-term, inhibitory effect on both basal and phenothiazine-stimulated secretion of prolactin.¹ They speculate that the lower . . .