Risks From Estrogen Reported
Six weeks after a large clinical trial on estrogen therapy was abruptly terminated, scientists have published the first details of the study -- revealing that, on average, the hormone caused 12 more strokes and six additional venous blood clots per 10,000 women each year.
Researchers for the Women’s Health Initiative also reported in today’s Journal of the American Medical Assn. that estrogen therapy for post-menopausal women did not provide protection against heart disease, as physicians once hoped.
Additionally -- in contrast to the effects of taking estrogen combined with progestin -- the scientists found that estrogen on its own did not raise the risk of breast cancer or lower the risk for colorectal cancer.
Estrogen therapy did benefit bone health, resulting in six fewer hip fractures per 10,000 women each year. However, because of the stroke and blood clot risks, other bone-building options should be tried first, said Dr. Barbara Alving, director of the Women’s Health Initiative and acting director of the National Heart, Lung and Blood Institute.
Though it still makes sense, and is safe, to temporarily take hormones to relieve menopausal symptoms such as hot flashes, “these findings confirm that estrogen-alone therapy should not be used to prevent chronic disease,” Alving said.
The Food and Drug Administration recommends that hormones be taken for as short a time and in as low a dose as possible.
The Women’s Health Initiative is a large-scale investigation into the role of hormones, diet and vitamins on the health of women after menopause.
One study of 16,608 women investigated the effects of taking estrogen with progestin. The study was halted several years early in 2002, after a safety monitoring board concluded that the increased risk of breast cancer, stroke, heart attack and blood clots outweighed the benefits of taking the hormones.
The estrogen-only study involved 10,739 healthy women who had had hysterectomies. (Such women do not need to take progestin, which is given to protect the uterus against estrogen-induced cancers.) Scheduled to end in March 2005, it was also halted after the National Institutes of Health decided that women taking the hormone were being placed at a slight but unjustifiable risk.
Women from both studies will continue to be monitored. A study of estrogen’s effect on dementia and memory is expected to be published in upcoming months.
