Estrogen Again

The results of the Women's Health Initiative (WHI)--the largest, most scientifically rigorous study of older women's medical issues ever conducted--continue to startle researchers, confuse the public and frustrate headline writers. Case in point: last week's report that taking estrogen for seven years does not increase the risk of breast cancer for many women. There is a lot of good news in that finding, as well as some important caveats.

In many ways, the story began four years ago when researchers halted a different part of the WHI--one that looked at the long-term health effects of taking the hormone combination estrogen and progestin (Prempro)--because of an increased risk of breast cancer and heart disease. (Women with a uterus who want to try hormone therapy must take both hormones because estrogen alone increases the risk of uterine cancer.) Two years later, the estrogen-only (Premarin) part of the trial, which focused on nearly 11,000 postmenopausal women who had undergone a hysterectomy, was stopped because of a slightly greater risk of stroke--although there was no overall boost in heart disease. Preliminary evidence at the time suggested that estrogen did not increase the women's risk of breast cancer. That was something of a surprise, so most researchers reserved judgment until the final analyses had been completed.

The results are now in and should reassure a lot of women. There is still no scientific justification for the long-term use of hormones after menopause to prevent such conditions as heart disease or dementia. But a shorter course of estrogen--seven years or less--is safe enough with respect to breast cancer and other health risks that it's a reasonable option for the treatment of severe menopausal symptoms. In other words, says Marcia Stefanick, one of the lead researchers, since there is no overriding safety concern, "the focus should be on your individual risk."

Here's where things get tricky. A closer look at the findings shows that women who have had a benign breast ailment, who score high on the so-called Gail model of breast-cancer risks or whose mother or sister had breast cancer are slightly more likely to develop breast cancer when taking estrogen supplements. In addition, all study participants, regardless of their breast-cancer risk, were more likely to have suspicious-looking mammograms that required biopsies to make sure that nothing was wrong.

So, if you have severe menopausal symptoms, have lost your uterus and don't have a high risk of developing breast cancer or blood clots, you can safely consider estrogen therapy for temporary relief. Eventually, as genetic tests based on blood samples from WHI participants start to be developed, investigators should be able to say even more precisely who is likely to benefit from estrogen treatment and who should avoid it. Meanwhile, stay tuned for more surprising WHI results.

THE WOMEN'S HEALTH INITIATIVE

> More than 160,000 women enrolled in the WHI studies. Of them, 27,347 participated in the two hormone trials

> The main purpose of the two trials was to find out if long-term hormone therapy prevents heart disease in older women. The answer was no

> Some doctors wonder whether hormones may benefit younger women--an issue the WHI did not address