Bone benefits slim from brief estrogen use, study says

December 07, 1993|By Laurie Garrett | Laurie Garrett,Newsday

A new scientific wrinkle further complicates women's choices about whether to go on estrogen therapy when they reach menopause.

One of the strongest arguments in favor of estrogen therapy has been osteoporosis, since the hormone slows calcium loss in older women, preventing the brittling of bones that can lead to fractures and crippled spines.

Most physician organizations that have addressed the issue have concluded that use of artificial estrogen for a few years during menopause can help prevent the dramatic calcium loss that normally occurs at that time.

But a recent study in the New England Journal of Medicine looked at more than 600 women averaging 76 years of age, and showed that the bone benefits seen with short-term estrogen use are, in the long run, minimal to nonexistent.

"Any way you look at it, whether or not to go on estrogen therapy is a tough decision," said the study's leader, Dr. David Felson of the Boston University Arthritis Center. "And my study didn't make it any easier."

Dr. Felson's team of researchers measured the bones of 670 Caucasian women living in Framingham, Mass., in 1988, assessed their earlier artificial estrogen use, and kept track over the years of their reported bone fractures. Most of the women in the study either had received no menopausal therapy, or had taken pure estrogen about 20 years earlier (as opposed to the currently popular mix of estrogen and progestins).

The study found that taking estrogen for less than seven years had no net protective effect on women's bones by the time they reached age 75, though it may have briefly slowed their bone-loss rates while they were on the drug.

In women who had taken estrogen for seven to 10 years, the net benefit by age 75 was about 3 percent more bone mass than in women who never took the hormone -- not enough to be considered significant, Dr. Felson said. The fracture rates among those women, and among those in the study who never took estrogen supplements, were roughly equivalent, though the non-users were more likely to have had broken bones when they were in their 60s.

What that means, Dr. Felson concluded, is that women who have family histories of osteoporosis or are otherwise concerned about the disease need to take estrogen for their entire postmenopausal lives, which could put them at risk for breast cancer, particularly if they have a family history of that disease.

"If you think you're going to get protection from taking it for five years, I'm sorry, but you're fooling yourself," he said. "What that says to women trying to make this choice is it's tough, real tough."

Dr. Michael Lockskin of the National Institute of Arthritis and Musculoskeletal and Skin Diseases in Bethesda, Md., agreed that the bone benefits of estrogen therapy wear off quickly when women cease taking the drug. But, he said, "The conclusion that a woman would have to take estrogen the rest of her life is not supported by the study, because there is no data on women who took estrogen for the rest of their lives."

To obtain such data, Dr. Felson would have to continue his study of the Framingham women for at least another 15 years, releasing conclusions on estrogen effects in 2008.

Recently Dr. Elizabeth Barrett-Connor, a prominent menopause researcher at the University of California, San Diego, published an osteoporosis study of white women living in a retirement community.

She found that no factor -- including estrogen use or non-use -- affected bone loss and osteoporosis more than the total number of reproductive years the woman had prior to menopause. During those reproductive years a woman naturally produces estrogen that strongly protects her bones.

According to the Barrett-Connor study, published in the American Journal of Public Health, no dietary or drug factor could offset the osteoporosis risks arising from a reproductive life that was shortened by an early natural or hysterectomy-induced menopause.

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