Tamoxifen has been used effectively to improve blood flow, reduce uterine contractility and pain in dysmenorrhea patients.
Tamoxifen is used for the treatment of both early and advanced estrogen receptor-positive (ER-positive or ER+) breast cancer in pre- and postmenopausal women.Tamoxifen increases the risk of postmenopausal bleeding, endometrial polyps, hyperplasia, and endometrial cancer; using tamoxifen with an intrauterine system releasing levonorgestrel might increase vaginal bleeding after 1 to 2 years, but reduces somewhat endometrial polyps and hyperplasia, but not necessarily endometrial cancer. Additionally, it is the most common hormone treatment for male breast cancer. It is also approved by the FDA for the prevention of breast cancer in women at high risk of developing the disease. It has been further approved for the reduction of contralateral (in the opposite breast) cancer. The use of tamoxifen is recommended for 10 years.
In 2006, the large STAR clinical study concluded that raloxifene is also effective in reducing the incidence of breast cancer. Updated results after an average of 6.75 years of follow up found that raloxifene retains 76% of tamoxifen’s effectiveness in preventing invasive breast cancer, with 45% fewer uterine cancers and 25% fewer blood clots in women taking raloxifene than in women taking tamoxifen.
Tamoxifen is used for ovulation induction to treat infertility in women with anovulatory disorders. It is given at days three to seven of a woman’s cycle.
Tamoxifen improves fertility in males with infertility by disinhibiting the hypothalamic–pituitary–gonadal axis (HPG axis) via ER antagonism and thereby increasing the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) and increasing testicular testosterone production.
Tamoxifen is used to prevent and treat gynecomastia. It is taken as a preventative measure in small doses, or used at the onset of any symptoms such as nipple soreness or sensitivity. Other medications are taken for similar purposes such as clomifene and the anti-aromatase drugs which are used in order to try to avoid the hormone-related adverse effects.
Tamoxifen is useful in the treatment of peripheral precocious puberty, for instance due to McCune–Albright syndrome, in both girls and boys. It has been found to decrease growth velocity and the rate of bone maturation in girls with precocious puberty, and hence to improve final height in these individuals.