Women who took hormone replacement pills had more advanced breast cancers and were more likely to die from them than women who took a dummy pill, raising new concerns about the commonly prescribed drugs, U.S. researchers said on Tuesday.
The study, published in the Journal of the American Medical Association, is the first to report more breast cancer deaths among women taking hormone replacement therapy. And it contradicts prior studies that suggest women taking the drugs had less aggressive, easier-to-treat breast cancers.
"As opposed to the prevailing thought of two years ago, that cancers associated with estrogen plus progesterone would be favorable and not much of a problem, we are actually showing they are associated with an increased risk of death from breast cancer," Dr. Rowan Chlebowski of the Los Angeles Biomedical Research Institute, who led the study, said in a telephone interview.
The findings include 11 years of follow-up from the Women's Health Initiative study, which in 2002 found women who took estrogen plus progesterone for five years had higher rates of ovarian cancer, breast cancer, strokes and other health problems.
Sales of U.S. market leader Wyeth's combined estrogen plus progesterone pill Prempro have fallen by about 50 percent since 2001 to around $1 billion a year. Wyeth is now owned by Pfizer.