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HRT Poses Yet Another Health Dilemma

Estrogen alone increases endometrial cancer risk, large British study finds

THURSDAY, April 28, 2005 (HealthDay News) -- A new British report presents women with a potentially cruel choice if they want to use hormone replacement therapy to ease the symptoms of menopause: The kind of therapy that does not increase the risk of breast cancer does increase the risk of endometrial cancer.

"We are now in quite a dilemma about what to say. There is quite a debate about what women should be doing," said Dr. Valerie Beral, a professor of epidemiology at the University of Oxford and lead author of the latest findings, culled from the Million Women Study, which appear in the April 29 issue of The Lancet.

The most immediate advice is that a woman "should take the lowest possible dose for the shortest possible time," said Louise Brinton, chief of the hormonal and reproductive epidemiology branch of the U.S. National Cancer Institute. She co-authored an accompanying commentary in the same issue of the journal.

However, Brinton added, "we still need more data to determine how best to prescribe hormones." The British study was relatively short-term, with a follow-up of only slightly more than three years, she noted. "The big question is how long a woman can take hormone replacement therapy before the risks overpower the benefits," she said.

That decision must be made by each individual woman, Brinton stressed. "The symptoms of menopause are extremely variable," she said. "Some women have symptoms severe enough to make their lives miserable. Some have no symptoms at all. Some women may not need hormones at all, others may need them for a long period of time. My concern is that we don't have long-term safety data."

The British study included 717,000 postmenopausal women, aged 50 to 64, who had no history of cancer and had not had a hysterectomy. Just under half of them reported that they had used some form of hormone replacement therapy.

The study produced a complex set of results, depending not only on the type of hormones used but also on the medication schedule and a woman's weight.

Women who took only estrogen had a higher risk of endometrial cancer than women who did not take replacement therapy, the researchers reported. The same was true of women who took only tibolone, a synthetic hormone that has not been approved for use in the United States.

There was no increase in endometrial cancer for women who took a combination of estrogen and progesterone. But a 2003 report on the Million Women Study said that that combination increased the risk of breast cancer.

In women who were overweight, combination therapy reduced the risk of endometrial cancer, with the reduction seen in overweight women who took the hormones in an off-and-on cycle or regularly. But cyclic combined therapy increased the risk of endometrial cancer in women who were not overweight.

Thus, any women seeking hormone replacement therapy "needs proper information," Beral said. "It is a very complex picture."

"We can't make global recommendations," Brinton said. "There must be individual decisions based on women's needs."

More detailed information to help guide those decisions should be coming in the years ahead, from the British study and from the Nurses Health Study in the United States, she added.

HRT's reputation as a safe method of easing menopausal symptoms has never recovered from the 2002 findings of a large, ongoing U.S. study known as the Women's Health Initiative. In that trial, early results indicated the regimen increased women's risks for heart attack, stroke, blood clots and breast cancer. Use of HRT among American women soon fell dramatically.

More information

The complete hormone-replacement story is told by the National Library of Medicine.

SOURCES: Valerie Beral, M.D., professor, epidemiology, University of Oxford, England; Louise Brinton, Ph.D, chief, National Cancer Institute hormonal and reproductive epidemiology branch, Bethesda, Md.; April 29, 2005, The Lancet
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