Health consequences of short- and long-term postmenopausal hormone therapy.

Some women take an estrogen preparation for as long as several years to ease symptoms of the menopause. Such women appear to have little or no alteration in their risk of endometrial cancer, especially if they are also taking a progestogen, and no alteration in their risk of breast cancer. Similarly, the incidence of fractures is unaffected by relatively short-term hormone use. The risk of ischemic heart disease also is reduced among women who currently take estrogens (with or without a progestogen), but the influence of duration of use on this association is uncertain. Postmenopausal women who take estrogens for an extended period of time (e.g., a decade or more) incur a sharply increased risk of cancer of the endometrium. This is largely abated by use of a progestogen for at least 10 days per month. Such long-term estrogen use, whether accompanied by a progestogen or not, may increase the risk of breast cancer slightly, but this is an area of great controversy, at present unresolved. The incidence of both myocardial infarction and fracture is substantially reduced in long-term users of menopausal hormones.