Estrogen replacement therapy (ERT): a form of therapy with estrogen hormones most commonly used to treat the symptoms of menopause. It reduces or stops the short-term changes of menopause such as hot flashes, disturbed sleep, and vaginal dryness. Estrogen replacement therapy is thought to help prevent osteoporosis, a consequence of lowered estrogen levels. Estrogen therapy has more recently been referred to without the use of the term "replacement" and is simply referred to as estrogen therapy or estrogen therapy.
While estrogen therapy may help prevent osteoporosis, it has been reported to be associated with health risks in some populations. Specifically, the Women's Health Initiative (WHI) data in 2002 showed that estrogen therapy alone in menopause led to an increased risk for strokes and blood clots. However, the women in this study were older and other research has suggested a possible protective effect against heart disease when taken early in the postmenopausal years. The definitive health risks and benefits of estrogen therapy have yet to be fully characterized. Vaginal estrogen therapy products help with vaginal dryness, more severe vaginal changes, and bladder effects but, since very little vaginal estrogen enters the circulation, it may not help with hot flashes or prevent osteoporosis .
The use of unopposed estrogen therapy (estrogen therapy alone without progesterone) is associated with an increase in the risk of endometrial cancer (cancer of the lining of the uterus). However, by taking the hormone progestogen along with estrogen, the risk of endometrial cancer is reduced substantially. Progestogen protects the uterus by keeping the endometrium from thickening (an effect caused by estrogen). The combination therapy of estrogen plus progestogen is called hormone therapy (HT, also formerly known as hormone replacement therapy or HRT).
The decision to take estrogen therapy or hormone therapy is best made together with a healthcare practitioner who can help explain the potential risks and benefits on a case-by-case basis. Estrogen therapy may not be appropriate for all women, for example, women with breast cancer, heart disease, or a history of blood clots.