For example, there is an inverse relationship between serum ferritin and estrogen levels, which causes iron stores to gradually increase after menopause.45 However, both serum ferritin and iron stores are still reportedly lower in postmenopausal women than in men.46,47 A consequence of these sex differences in iron metabolism is that high serum iron levels are much more prevalent in men than women and have been associated with increased cancer risk.41 We observed truncated survival only in female mice implanted with Hfe-overexpressing tumor cells. This evidence concerns the gene HFE and cancer.