Clearly, melatonin-GR interactions will influence hypothalamic fluxes that may be differentially relevant in different types of cancer, such as gonadotrophin releasing hormone (GnRH) regulation of pituitary luteinizing hormone in the regulation of ovarian, breast and prostate cancers [139–141], with relevance as to how other types of ovarian conditions, such as polycystic ovary syndrome (PCOS) [142, 143] and endometriosis [144, 145], are associated with ovarian and breast cancer risk. Here, GNRH1 is linked to polycystic ovary syndrome.