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HRT Raises Risk of Breast Cancer Death

Combined Hormone Replacement Therapy May Be more Deadly for Some
WebMD Health News

Aug. 7, 2003 -- Combined hormone replacement therapy (HRT) using estrogen plus progestin may not only increase a woman's risk of breast cancer, but it may also make her more likely to die from the disease.

A British study shows for the first time that HRT users are more likely to die of breast cancer than women who have never used HRT, and the breast cancer risks associated with combined estrogen-progestin hormone therapy are up to four times greater than those associated with estrogen-only HRT.

The study, published in the Aug. 9 edition of The Lancet, involved about 1 million women between the ages of 50 and 64 and also confirms previous studies that found HRT slightly raises the risk of breast cancer in postmenopausal women.

Half of the women were HRT users. A total of 9,364 breast cancers were reported after an average of 2.6 years, and 637 deaths were reported after an average of 4.1 years.

Researchers found the risk of breast cancer increased the longer a woman used HRT, but this effect wore off within a few years after stopping HRT. Women who had used HRT at the start of the study had an almost 70% higher risk of developing breast cancer and a 22% higher risk of dying from it than women who never used HRT. Past users of HRT did not have an increased risk of the disease or death from it.

The study showed that current use of combination HRT was associated with a higher risk of breast cancer than estrogen-only HRT. The longer HRT was used, the greater the risk. Also, the increased risk varied on the type of estrogen and progestin as well as whether the women took the hormones continuously or periodically.

Researchers estimate that for every 1,000 postmenopausal women who take HRT for 10 years, use of estrogen-only HRT will cause an extra five breast cancer cases and combined HRT will cause an extra 19 cases.

"Combined estrogen-progesterone HRT is usually prescribed for women who still have a uterus, to avoid the increased risk of cancer of the uterus caused by estrogen-only therapy," says researcher Valerie Beral, professor at Cancer Research UK, in a news release.

"Since our results show a substantially greater increase in breast cancer with combined HRT, women need to weigh the increased risk of breast cancer caused by the addition of progestin against the lowered risk of uterine cancer," says Beral. "Comparing the risks is by no means simple, and women may well want to discuss options with their doctor."

In an editorial the accompanies the study, Chris van Wheel and colleagues from the University of Nijmegen, Netherlands, say these findings are in line with two recent studies published in The Journal of the American Medical Association that found a higher risk of advanced or invasive breast cancers in combination HRT users.

"The problem is in those women who are already, often for a long time, taking HRT -- estimated at between 20% and 50% of all women 45-70 years of age in the western population," they write. "This group should discontinue HRT use as soon as possible.

"Discontinuing HRT should be suggested in as supportive a way as possible, because no one will benefit from panic or over-reaction: general practitioners need to use the opportunities arising from their regular contacts with patients taking HRT to discuss treatment-related risks, to give advice about stopping, and to offer alternative support."

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