The U.S. Preventive Services Task Force has recommended against the use of combined estrogen and progestin therapy for preventing cardiovascular disease and other chronic conditions in postmenopausal women.

The Task Force, sponsored by the Agency for Healthcare Research and Quality, found evidence for both benefits and harms of combined estrogen and progestin therapy, one of the most commonly prescribed hormone regimens. However, the Task Force concluded that harmful effects of the combined therapy are likely to exceed the chronic disease prevention benefits for most women.

The Task Force further concluded that the evidence is insufficient to recommend for or against the use of estrogen alone for prevention of chronic conditions in postmenopausal women who have had a hysterectomy. A study of estrogen therapy in women who have had hysterectomies is continuing as part of the National Institutes of Health (NIH) Women's Health Initiative because it has not yet found clear benefit or harm. Estrogen alone, or estrogen and progestin together, are commonly referred to as hormone therapy or hormone replacement therapy.

An estimated 14 million American women take hormone therapy to help relieve hot flashes and other menopausal symptoms as well as to prevent chronic conditions such as heart disease.

The scientific review for the Task Force examined hundreds of studies, including a recently terminated trial within the NIH's Women's Health Initiative, which reported the effects of taking combined estrogen and progestin therapy on a variety of chronic diseases. The Task Force concluded that combined hormone therapy could increase bone mineral density and reduce the risk of fractures and may reduce the risk of colorectal cancer.

Yet, they found equally strong evidence that combined hormone therapy increases the risk for breast cancer, blood clots, stroke, and gallbladder disease. In addition, evidence reviewed by the Task Force suggests that hormone therapy does not reduce the risk of heart disease and that estrogen and progestin combined actually increase the risk of heart attacks. The effects of hormone therapy on dementia, cognitive function, and ovarian cancer are uncertain.

In 1996, the Task Force found insufficient evidence to recommend for or against taking hormone therapy to prevent chronic conditions. That did not, however, stop pharmaceutical companies and medical doctors from prescribing the drugs, which constitute a multi-billion dollar industry.