Is Estrogen for You? At menopause, the risks of hormonetherapy are not the same for everyone.(Cover story)

Byline: Joann E. Manson, M.D., DR.P.H., and Shari S. Bassuk, SC.D. (Manson and Bassuk are affiliated with Harvard Medical School and Brigham and Women's Hospital. They are the authors of "Hot Flashes, Hormones and Health" (McGraw-Hill), to be published later this year. For more information on menopause and hormone therapy, go to health.harvard.edu/NEWSWEEK.)

Women entering menopause are understandably confused about whether to take hormone therapy. Estrogen is the most effective way to beat hot flashes. It also eases vaginal dryness and may improve your sleep, mood and concentration. But many women are wary after recent studies showed that taking hormone therapy may increase vulnerability to heart disease, causing the risks to outweigh the benefits. What do you need to know to make your decision?

A little history helps. Until a few years ago, many doctors believed that estrogen protected against heart disease, a leading killer of women in developed countries. Large observational studies found lower rates of heart disease and bone fractures in women taking estrogen. Those same studies also identified risks from hormone therapy: higher rates of breast cancer, stroke and blood clots in the legs or lungs. Recently, however, reports from randomized clinical trials, including the Women's Health Initiative, have suggested that hormone therapy might actually increase the risk of heart disease. Because randomized clinical trials provide stronger evidence than observational studies, these findings were major news and persuaded many women (and their doctors) to steer clear of hormone therapy.

In just a few years, the pendulum of public opinion shifted from the position that hormone therapy is good for all to believing that no one should take it. Both views are oversimplifications. As researchers who have conducted in-depth studies of hormone therapy, we believe that the "one size fits all" approach is misguided. Recent research from our group and others strongly suggests that a woman's age and time since menopause, as well as her health history, are the most important factors in the benefit-risk equation. Hormone therapy is more likely to be beneficial if started early in menopause (as in the observational studies that showed favorable results for heart disease) and harmful if started later (generally the case in the randomized trials, which showed negative results).

Why this paradox? Estrogen seems to slow the early stages of atherosclerosis. Once advanced atherosclerotic plaques develop, however, estrogen may make them more fragile and more likely to cause heart attacks by rupturing and forming clots. In many women, advanced plaques begin to form by the age of 60. So a woman who starts hormone therapy when she already has advanced atherosclerosis may be particularly prone to having a heart ...