A woman's risk for breast cancer declines within about two years after ending hormone replacement therapy, according to a new analysis of the 2002 Women's Health Initiative, the Wall Street Journal reports. The study's authors said that their finding explains declines in breast cancer rates in the U.S. since 2002, when the National Institutes of Health warned against overuse of HRT post-menopause after a WHI study showed that women taking a combination of estrogen and progestin had higher rates of heart attack, breast cancer and stroke. The study aruges that the warning prompted many women to stop taking HRT and that breast cancer rates quickly fell in the U.S. and other industrialized countries.
In the new study -- published Wednesday in the New England Journal of Medicine -- researchers from the WHI re-examined medical records from before and after 2002 for the 16,608 women in the original study. Half of the women had been assigned to take Wyeth's estrogen-progestin combination Prempro until 2002. The study found that the added risk for breast cancer for women taking Prempro fell about two years after the women stopped taking the hormones, a decline similar to that in the U.S. population. According to federal statistics, about 210,000 U.S. women were diagnosed with breast cancer each year before 2002, but the rate quickly dropped to less than 190,000 and remained there through 2005, the most recent year for which data are available. Rowan Chlebowski, lead author of the new study, said, "These are nonconventional analyses, but I think this is the best data we have," adding, "For two to a few more years, combined hormone therapy is safe. This [study] really suggests there's a great benefit to women for stopping, because the risk goes down almost immediately" (Winstein, Wall Street Journal, 2/5) The study also found that the risk of breast cancer doubled after five years for women taking HRT, compared with those not taking hormones (Park, Time, 2/4).
Some experts are hesitant to directly tie the decline in HRT use to the decrease in breast cancer rates. Joseph Camardo -- Wyeth's senior vice president of global medical affairs -- said, "It may be coincidence that as mammography was increasing in the late '90s, more and more cancers were being detected earlier, and when the study was halted, there's a coincidence in time," with less screening and fewer cancers now being found. Wyeth faces lawsuits from more than 11,000 women over Prempro (Wall Street Journal, 2/5). According to USA Today, mammography rates among women in the study didn't change in the two years after halting HRT (Rubin, USA Today, 2/5). Avrum Bluming of the University of Southern California said that the decline in breast cancer rates was too rapid to be attributed to a "decrease in the cancer-producing effect" of HRT, adding, "You don't see a decrease in six months" (Wall Street Journal, 2/5). Jonathan Berek, chair of obstetrics and gynecology at Stanford University School of Medicine, said the study is not an "indictment" of HRT use but that it does reaffirm that "like all medicines, hormones have their benefits and risks, so they have to be used very judiciously and for a short time" (Time, 2/4).
NPR Coverage
NPR's "All Things Considered" on Wednesday reported on the study. The segment includes comments from study co-author Marcia Stefanick of the Stanford Prevention Research Center; JoAnn Manson, chief of preventive medicine at Brigham and Women's Hospital; and Deborah Armstrong of the Johns Hopkins Kimmel Cancer Center (Aubrey, NPR, "All Things Considered", 2/4).
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