One theory posits that high levels of gonadotropins increase risk, implying that PMH use might decrease risk by reducing these levels (follicle-stimulating hormone (FSH) and leutinising hormone (LH)), but as the declines associated with PMH use are small, the benefits might be outweighed by estrogen-induced proliferation of ovarian cells (Cramer and Welch, 1983; Fraser et al, 1998); it has been estimated that as many as 60% of ovarian tumours are estrogen receptor-positive (Cunat et al, 2004). Here, ESR1 is linked to ovarian neoplasm.