Timing, Type of HRT May Determine Breast Cancer Risk

Sept. 17 -- WEDNESDAY, Sept. 16 (HealthDay News) -- The timing and type of hormone replacement therapy women take to relieve menopausal symptoms seem to determine the degree of breast cancer risk they face, a new French study suggests.

Overall, starting estrogen-progestagen therapy soon after menopause appears to boost the risk of breast cancer, even when only used for short periods of time, according to the study, which was published in the Sept. 14 online issue of the Journal of Clinical Oncology.

Women who began the therapy in the three years after menopause and took it for two years or less had a 54 percent higher risk of breast cancer compared to those who never used the therapy, said study co-author Francoise Clavel-Chapelon, a researcher at the Institut Gustave Roussy in Villejuif, France.

However, they found an exception.

"This 54 percent increase in risk is an average, but does not seem to apply to estrogen-progesterone menopausal hormone therapy, for which no increased risk was observed when used two years or less, even close to menopause," she said. But she noted the risk may still be present, and it was simply not found in the study due to such factors as lack of statistical power.

Many types of progestagens were taken by the women in the study; the finding that progesterone may be safer needs to be confirmed, she stressed.

The new study adds to a growing body of research that is sorting out the risks and benefits of hormone replacement therapy. Until the end of the 1990s, the therapy was viewed as largely beneficial, the authors noted. But with the release of the Women's Health Initiative trial in 2002, research began to show the therapy boosted the risk for blood clots and breast cancer, and did not protect against heart disease, as originally believed.

Later on, some researchers hypothesized that the timing of therapy might affect patients' heart disease risk. The French researchers decided to see if timing might affect breast cancer risk.