The Latest Wisdom on Hormone Therapy
The news almost five years ago that hormone therapy might harm rather than protect women's health surprised researchers and led to a sharp decline in the number of women taking the drugs. Since the Women's Health Initiative findings showed that combined estrogen and progesterone therapy raises the risk of stroke, heart disease, and breast cancer, more studies have trickled out, refining what we know about how hormones alter the risk of those diseases. Three released in the past month have added to the evidence, including two this week examining hormone therapy's link to breast and ovarian cancer. Here's a wrap-up of the changing wisdom on HT:
What's the latest news on hormones and breast cancer?
The number of new breast cancer cases fell by nearly 7 percent in 2003. Now, a study published in the New England Journal of Medicine shows that the rate leveled off and stayed low in 2004. The findings support–though don't confirm–that the mass abandonment of hormone therapy in mid-2002 played a role in the decline of breast cancer incidence. In other words, they suggest the WHI study was right.
What kind of evidence backs that up beyond the timing of the decline?
Two things, says Peter Ravdin, an oncologist at the University of Texas M.D. Anderson Cancer Center in Houston and the leader of the study. First, the drop occurred only in women over 50, which is exactly who was using hormone therapy en masse until 2002. "The other strong link is that the majority of the decrease is in estrogen receptor positive breast cancers," he says. Those tumors are fueled by estrogen, either when it's produced naturally by the woman or taken via hormone therapy.
Still, this kind of study can never prove the role of hormones. Other proposed causes for the drop include a drop in the detection of new cases as the number of women being screened by mammograms has declined. The rate of screening mammography dropped 3.2 percent in women ages 30 to 65 between 2000 and 2003. No one knows why, but possibly women who went off HT thought their risk for breast cancer was low enough that they could skip their annual mammogram.
And what about ovarian cancer?
Another study, published this week in the online version of the Lancet, attributed to HT an extra 1,000 ovarian cancer deaths between 1991 and 2005 in the U.K. Researchers found more ovarian cancer in hormone therapy users–about 2.6 cases per thousand women using hormones, compared with 2.2 cases per thousand in women who weren't using them. Ovarian cancer increases weren't noted in the 2002 WHI data, but that study was far smaller: just under 17,000 women, compared with nearly a million in the U.K study. So an increase in the disease might not have shown up. Mary Daly, director of the Margaret Dyson Family Risk Assessment Program at Fox Chase Cancer Center in Philadelphia, says the link isn't definite, however. "Maybe women who take hormone therapy are different in some other way" that might raise their risk of the disease, she says.
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