PRL and cancer: Sex-related protein hormones, such as prolactin (PRL), luteinizing hormone (LH),4 follicle-stimulating hormone (FSH), and gonadotropin-releasing hormone (GNRH),5 are mainly implicated in cancers of reproductive tissues, including prostate, ovarian, and breast tissue.6 Growth hormone (GH) has been implicated in hepatocellular carcinoma,7 possibly because it undergoes pulsatile secretion into the plasma in males, and constant secretion in females.8 For the sex steroid hormones, much more abundant information exists on cancer development in nonreproductive organs relative to protein hormones.