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Good News ... And Lots of Questions

It was big news this week when researchers from the M. D. Anderson Cancer Center in Houston reported that breast-cancer rates dropped after millions of women stopped taking hormone therapy to relieve menopausal symptoms. But does that mean that these hormones (basically estrogen and sometimes a progestin) actually cause breast cancer? That’s the provocative question raised by the study. The researchers found an overall 7 percent decline in breast-cancer incidence in 2003, a year after a major study of hormonescalled the Women’s Health Initiative (WHI) was halted early because of increased breast cancer and heart disease among participants. The steepest decline, 12 percent, occurred in the number of women diagnosed with a kind of breast cancer that is especially sensitive to hormones.

Another recent study, by researchers in California, echoes these findings. Christina Clarke, an epidemiologist at the Northern California Cancer Center, and her colleagues found that breast-cancer rates in California dropped even more steeply after the WHI—12 percent fewer in 2003 and 2004. Clarke attributes the difference to the fact that California women were more likely to use hormones than women in other states. “We rarely see changes this dramatic over such a short time period,” Clarke says.

But while the connection may seem clear, researchers caution that they really won’t understand the meaning of the drop until they see national numbers for 2004, which are expected next spring, and analyze these and other statistics more carefully. Scientists need to know whether there’s a difference in breast-cancer rates between women who’ve been on hormone therapy and those who haven’t and what happens to former hormone users years after they quit. It’s possible that stopping hormone therapy merely slowed the growth of tumors that will eventually emerge—which means breast-cancer rates could rise again. Without all that data, the current numbers show only an association, not causation, says Marcia Stefanick, chair of the WHI steering committee and a professor of medicine at Stanford University.

Doctors who treat menopausal women say the new numbers shouldn’t be the only basis for a decision on whether or not to use hormones. “This isn’t a cause for alarm,” says Dr. JoAnn Manson, chief of the Division of Preventative Medicine at Brigham and Women’s Hospital in Boston. “It has been known for a while that estrogen plus progestin increases the risk of breast cancer.” But, she adds, that shouldn’t necessarily stop women with severe symptoms from using low-dose hormones for two or three years. “I think it underscores the importance of looking at your personal risk factors for breast cancer and cardiovascular disease,” says Manson, author of “Hot Flashes, Hormones & Your Health,” “and whether the benefits are likely to outweigh the risks.”

That emphasis on balancing risks and benefits is an important legacy of the WHI, says Clarke. “I think we’re really moving into an era in science where medicine is going to become personalized. It really depends on you and how bad your symptoms are and what your personal risk is for breast cancer. Do you have a history? Have you been diagnosed with a benign breast tumor before? I think you have to put all those things together with your doctor to come up with a decision.”

Since the WHI, pharmaceutical companies have begun offering many more different forms and dosages of hormone therapy—not just pills, but also lotions, patches and local therapy for symptoms like vaginal dryness. All these give women many more choices. But researchers say that if you do take hormones, it’s important to reconsider that decision regularly with your doctor—at least once a year if not more. “We don’t know how long you can go before your risk exceeds some benefits,” says Brenda K. Edwards, associate director of the surveillance research program at the National Cancer Institute. “Women and their physicians need to keep that in mind.” When it comes to hormone therapy, about the only thing that’s certain is that we need more information.

Barbara Kantrowitz

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