GWAS studies in women with endometriosis revealed numerous genes, including the genes associated with uterine development and stem cell function (WNT4), ovulatory function (ESR1, FSHB), and those regulating the activity of estrogen and estradiol biosynthesis (ESR1, GREB1, SYNE1, CYP2C19, CCDC170); most of these genes are also associated with ovarian cancer [68,69,70]. This evidence concerns the gene ESR1 and ovarian cancer.