Estrogen Discouraged for Disease Prevention
The findings are being published just over a month after the estrogen-only arm of the prevention study known as the Women's Health Initiative (WHI) was halted early. The study concludes that estrogen alone does not appear to affect heart disease. Earlier results showed that combination estrogen/progestin treatment increased heart disease risk.
But the researchers also concluded that estrogen therapy alone in postmenopausal women, like combination treatment, appears to increase the risk of stroke.
They say that the increased risk of stroke associated with the long-term use of estrogen alone outweighed any of the disease-prevention benefits found during the study.
In a news conference held Tuesday morning to discuss the findings, National Heart, Lung and Blood Institute Acting Director Barbara Alving, MD, said it is now clear that hormone therapy is not the disease-prevention panacea it was once believed to be.
"Hormones are certainly very appropriate for the treatment of menopausal symptoms, but they should be used at the lowest effective doses for the shortest possible time," she said. "For the prevention of diseases such as cardiovascular disease, hormone therapy is not the answer."
The WHI estrogen-only trial included nearly 11,000 healthy postmenopausal women aged 50-79 who had had a hysterectomy. They were treated daily with either the widely prescribed estrogen formulation Premarin or a placebo. The average age of the women at the time of enrollment was 64, and the women took the estrogen or the placebo for an average of seven years.
The study showed that women taking Premarin did not have a lower risk of heart disease. But women taking estrogen alone did have a significantly higher risk of stroke -- 39% increased risk compared with women taking placebo.
The findings are published in tomorrow's issue of TheJournal of the American Medical Association.
Among the other findings reported in the newly released analysis:
- Long-term use of Premarin was associated with a 39% reduction in the risk of hip fracture. In earlier studies, combination estrogen/progestin treatment also had this effect.
- Premarin use was not associated with an increased risk of breast cancer. Previous studies have linked estrogen/progestin combination treatment to an increase in breast cancer.
- Treatment with estrogen alone was linked to an increase in deep vein blood clots in the legs but did not appear to increase the risk for blood clots in the lungs.
- The use of Premarin was not found to affect colorectal cancer risk. Combination estrogen/progestin treatment decreased the risk.
The WHI is also evaluating the use of estrogen for the prevention of age-related dementia and memory loss, and these findings should be published in about two months, Alving said.