C In what is shaping up as one of the most controversial topics in women's health, a 10-year study of nearly 50,000 women has found that estrogen taken after menopause cuts in half the risk of heart disease, the leading killer of women.
Researchers from Harvard Medical School and Brigham and Women's Hospital in Boston report today in the New England Journal of Medicine on the largest estrogen study yet, done as part of a national health survey of female nurses begun in 1976.
Among 48,470 women followed for 10 years, the researchers found, the risk of major coronary disease among women taking estrogen after menopause was half that of women who did not take the hormone artificially. The result was basically the same even when the scientists factored in smoking or high blood pressure, which are already shown to cause heart disease.
The study found a similar reduction in the risk of a fatal heart attack but found no effect on the risk of stroke.
Although most experts believe more study is needed, the growing evidence suggests estrogen might one day be used routinely as a preventive heart drug, a development primarily affecting the 30 million female baby-boomers now approaching the end of fertility. Heart disease is the leading killer of women and men.
Still, one women's health group said it was not convinced of the study's validity and is holding to its view that doctors should stop trying to use drugs to "fix" menopause, which they said is a natural process and not a disease.
Estrogen is produced naturally in a woman's body, but the level of the hormone drops when menstrual periods cease. Given orally, estrogen is acclaimed as a remedy for the discomfort and hot flashes that accompany menopause and 50 percent of those who take it also avoid the crippling thinning of the bones that often afflicts older women.
But as a preventive drug, estrogen is shunned by millions of women and their doctors because some studies have suggested it raises slightly the risk of breast cancer and less slightly the risk of cancer of the uterine lining.
Then again, estrogen has been linked to a lessening of other
In the bloodstream, it seems to lower levels of cholesterol implicated in heart disease and death.
Perhaps no other drug has produced more contrary, last-week-it-was-bad-for-you-this-week-it's-good-for-you evidence than estrogen.
Dr. Meir J. Stampfer, the lead author of the study, said the study "comes as close as you can" to proving that estrogen works at substantially preventing heart disease. An accompanying editorial states that benefit alone far outweighs the risk that small numbers of women might develop cancers linked to estrogen-replacement therapy.
"I certainly would shy away from making any blanket recommendation that women take it," Stampfer said. "But I would say the vast majority of women ought to consider taking it." The authors call for estrogen trials among women with heart disease and further study of the effects of another hormone, progestin, which is often prescribed with estrogen to prevent a return of bleeding.
"We are not surprised and we are still not convinced," Cynthia Pearson, program director for the National Women's Health Network in Washington, D.C., said of the Harvard study. While "very large and well-done," the study's validity was limited, Pearson said, by its having to rely on data retrospectively gathered from women who had made their own decisions about whether to seek estrogen.
"Women could choose on their own whether to take estrogen. And it's likely those women are different from women who didn't," Pearson said.
While 14 of 15 other smaller studies have suggested estrogen use halves the risk of heart disease, no large-scale, controlled study of women has ever been done that would prove the connection once and for all.
Pearson said her group would continue to advise that only those women at risk of osteoporosis -- thinning of the bones -- and a few other ailments consider taking estrogen.
Menopause is a natural function and a woman's own estrogen levels are "naturally programmed to change and diminish," she said.
But Dr. Deborah A. Metzger, an assistant professor of obstetrics and gynecology at the University of Connecticut Health Center, considers the loss of natural estrogen as a deficiency. While menopause is natural, she said, large numbers of women living 35 years or more beyond menopause is a 20th-century phenomenon, made possible only by the invention of artificial, lifespan-prolonging drugs.
The fear of breast cancer, which has been statistically related to estrogen but never proved as cause, has been "blown all out of proportion" in comparison with estrogen's "silent benefits," Metzger said. Those silent benefits make up the continued good health she said many women would not have if not for their regular ration of estrogen.
"If you are going to have a longer life, you might as well live it as a healthy woman," she said.