Elevated levels of estrogens may increase the severity of breast cancer, as sex hormones can cause hyperplasia and differentiation at estrogen receptor sites. While officially indicated for women, this drug has proven effective in the off-label use of reducing estrogens (in particular and more importantly, estradiol) in men. Excess estradiol in men can cause benign prostatic hyperplasia, gynecomastia, and symptoms of hypogonadism. Study data currently suggests that dosages of 0.5 mg to 1 mg a day reduce serum estradiol by about 50% in men, which differs from the typical reduction in postmenopausal women. However the reduction may be different for men with grossly elevated estradiol.