Among the many questions about hormones prescribed for menopause is whether a woman's health risks change after she stops taking the pills. A new study shows that virtually all the benefits disappear but that a slightly higher risk for breast and other cancers persists for at least three years after stopping the drugs.
The data come from a major study by the Women's Health Initiative that looked at 16,000 women who used the estrogen and progestin combination drug Prempro, made by Wyeth.
Reporting in today's Journal of the American Medical Association, the study's investigators urge caution in interpreting the results, noting that a woman's individual risk remains small. The excess cancer risk among former hormone users translates to an added annual risk of 0.3 percent for an individual woman, or three additional cases of breast or other cancers a year among 1,000 women.
The findings do not change recommendations for hormone use, which advise that women consider using hormones only if they have moderate to severe hot flashes and other symptoms, and only at the lowest dose and for the shortest possible time.
"What we found in the study is quite consistent with the current guidelines," said Gerardo Heiss, the report's lead author and a professor of epidemiology from the University of North Carolina at Chapel Hill. "There is no reason for alarm. The absolute risk is of small magnitude."
One of the biggest benefits of hormone drugs, an improvement in bone health, all but disappeared during the three years after women stopped taking the drugs. But risks like blood clots, stroke and heart attacks originally seen among older hormone users in the study also quickly dropped back to normal rates once the women stopped the drugs.
The research was halted in mid 2002 because older women in the study were at higher risk for heart attacks if they began using hormones. The findings changed the medical community's views on hormone therapy, which was once used as a treatment to prevent chronic disease. Today, hormones are advised only for the treatment of moderate to severe hot flashes and other menopause symptoms, and doctors typically prescribe far lower doses of the drugs than those used in the study.
The report focuses on the three years after the end of the study, comparing the health of women who took hormones with that of participants who took placebos.
The Women's Health Initiative investigators have not yet analyzed the part of the study concerning women with hysterectomies who used only estrogen. (Progestin is taken only if a woman still has a uterus to protect her from endometrial cancer.) In that group, overall breast cancer rates were lower among hormone users, but the data failed to reach statistical significance.