CNN — Scientists from the WHI released what they say is the definitive study on the safety of hormone replacement therapy (HRT) on October 1.
The bottom line: It's OK for most healthy women who have just entered menopause to take hormones for a short period of time, but the researchers do not recommend it for long-term use. The results are published in this week's Journal of the American Medical Association.
Hormone replacement therapy is used to replace estrogen and other female hormones that are no longer produced after menopause. For decades, doctors thought HRT was good for women's hearts and prescribed it, in part, to prevent heart disease. About 40 percent of menopausal women used these hormones.
In the 1990s, more than 27,000 women were enrolled in a clinical trial through the WHI. Scientists wanted to find out if HRT really prevented heart disease and other chronic diseases. But in 2002, a major part of the trial using two kinds of hormones (estrogen plus progestin) was suspended. Researchers found some of the participants had serious health problems, including an increased risk of coronary heart disease, breast cancer and stroke. Two years later, the remainder of the clinical trial, involving women who had hysterectomies and were on only one hormone (estrogen), was also shut down due to health concerns.
When the WHI study was suspended, it received a lot of attention, both in the medical world and in the media. Many doctors stopped prescribing oral HRT. Today only about 10 percent to 15 percent of menopausal women still take them, experts say.
For this study, scientists looked back at 13 years of research on the WHI participants. The main message is: Most menopausal women should not use long-term hormone therapy for the purpose of preventing heart disease or other chronic diseases, says Dr. JoAnn Manson, one of the principal investigators of the WHI trial and Chief of Preventive Medicine at Brigham and Women's Hospital in Boston, Massachusetts.
The WHI research found older women taking HRT are at a higher risk of blood clots, stroke and, in some cases, heart attacks.
But for most healthy women who are beginning menopause and suffering severe symptoms such as hot flashes and trouble sleeping, HRT can be a good option.
"It's very likely that the quality of life benefits will outweigh the relatively small risk of having an adverse event," Munson says.
However, Munson adds, women who have a history of heart disease or breast cancer may want to avoid HRT.
Some observers hope this study will put to rest the debate over HRT. Over the years, some doctors have been critical of the way information from the WHI HRT trials has been interpreted.
"There are some risks and there are some benefits, but the risks in the grand scheme of things are not nearly as great as they have been portrayed," said Dr. Holly Thacker, director of the Cleveland Clinic Center for Specialized Women's Health in Cleveland, Ohio.
"Many of my patients still fear them, out of proportion to the data. This result helps put them into perspective once again and ought to be reassuring to women with average risk," says Dr. Nanette Santoro, chair of the Department of Obstetrics and Gynecology at the University of Colorado in Aurora, Colorado.
About 15 percent to 20 percent of women in early menopause have moderate to severe symptoms and might benefit from taking HRT, according to Manson. Health care providers now often prescribe lower doses of oral HRT or potentially safer options such as the hormone patch, gels or vaginal creams.