Menopausal hormone therapy and breast cancer risk.

This narrative review analyses the customization of Menopause Hormone Therapy in the context of breast cancer risk in women with premature ovarian insufficiency (POI) and with menopause at a normal age. Women with Idiopathic POI, FMR-1 premutation or Turner syndrome, if left untreated, may have lower breast cancer risk compared to the healthy age-matched female population. These women should be treated with MHT until the age of 50, as the risk of breast cancer is equal to that of normally menstruating women. Carriers of BRCA 1 & 2 mutation after risk-reducing bilateral salpingo-oophorectomy (RRSO), without a personal history of cancer, have an increased breast cancer risk, but may probably be treated with MHT till the age of 50. POI resulting from endometriosis or cancer related treatment is discussed in a separate paper in this issue. In peri- and postmenopausal women with menopausal symptoms and/or risk factors for osteoporosis in need of MHT, the individual breast cancer risk can be evaluated using internet-based calculators. In most women the 5-year-breast cancer risk is low (<3%) and MHT is a safe option. MHT should be prescribed with caution in women who have an intermediate risk (3-6%) and should not be prescribed in those who have a high risk of breast cancer (>6%). Oestrogen-only MHT and oestrogen-progestogen MHT containing micronized progesterone or dydrogesterone are associated with lower breast cancer risk compared to other combined MHT regimens.