WASHINGTON - The long-term risks of taking hormone replacement therapy outweigh the benefits for postmenopausal women, researchers said Tuesday.

Researchers across the U.S. had been looking into the health effects of taking the hormones estrogen and progestin in combination. Some 16,000 women between the ages of 50 and 79 took part in the study. The synthetic hormones replace the estrogen women lose as they age, and can help relieve the symptoms of menopause, such as hot flashes and night sweats.

The randomized, controlled study was due to continue until 2005, but researchers ended it three years early after finding the combination appears to slightly boost the chances of developing breast cancer. It was thought that hormone replacement therapy (HRT) might help prevent heart attacks and strokes in postmenopausal women, but the government-funded research suggests the drugs don't do that either.

The National Heart, Lung and Blood Institute sponsored the study as part of a larger project called the Women's Health Initiative. The latest results appear online in the July 9 issue of the Journal of the American Medical Association.

"We never had good data that (HRT) prevented heart attacks or strokes, but people extrapolated based on some mechanisms," said McMaster University's Dr. Salim Yusuf, who is on the monitoring board that recommended the study be stopped.

"Now we know those preliminary studies were wrong and this is the first definite study to test it and provide conclusive evidence," Yusuf added.

The data mean that among 10,000 women, there would be seven more women with coronary heart disease events (compared to the placebo group), eight more breast cancer cases, eight more strokes, and 18 more women with blood clots. On the plus side, there would be six fewer cases of colorectal cancer and five fewer hip fractures.

Although the increased risk is relatively small for individual women, the results are significant when you count up how many women could be taking HRT. Don't panic but see your doctor.

"The bottom line is that estrogen plus progestin is not a viable option to prevent chronic disease," said Dr. Gerardo Heiss, professor of epidemiology at the University of North Carolina at Chapel Hill School of Public Health. Heiss is a member of the Women's Health Initiative steering committee.

An editorial accompanying the study was more definitive. "The study provides an important answer for generations of healthy postmenopausal women to come who do not use estrogen/ progestin to prevent chronic disease," wrote Dr. Suzanne Fletcher of Harvard Medical School.

The study looked at PremPro (called PremPlus in Canada), the most popular estrogen progestin combination. But scientists don't know whether the results would apply to lower-dose pills, skin patches or estrogen-only therapies in women who have had their uterus removed.

Investigators say an estrogen-only study on women who've had hysterectomies should be completed in 2005. The study's authors say women taking estrogen long after menopause shouldn't panic, but they should talk to their doctors about easing themselves off the drugs. For women who are just entering menopause and are bothered by the symptoms, they should plan to stay on the drugs for only a few years.

Written by CBC News Online staff

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