Hormone trial halted due to cancer, heart risk

Last Updated: 2002-07-09 10:00:45 -0400 (Reuters Health)

WASHINGTON (Reuters Health) - Researchers announced Tuesday that they have halted one of the largest and best-designed studies of hormone replacement therapy because women taking the hormones after menopause had a greater risk of breast cancer, heart attack, stroke and blood clots than those who did not take the drugs.

More than 6 million women in the US currently take estrogen/progestin combination therapy for a variety of reasons, including relief of hot flashes and other menopausal symptoms. The hope--and the hype--has been that such hormones would also confer a number of other advantages, including a reduced risk of heart disease. The study suggests that when women take the drugs for more than about 5 years, the risks of the hormones clearly outweigh the benefits.

However, Dr. Jacques Rossouw said women who have participated in the trial, as well as other patients taking this combination, "should not be unduly alarmed," since the risk to an individual patient is small.

However, they should discuss the findings with their doctor, he said.

"Women with a uterus who are currently taking estrogen plus progestin should have a serious talk with their doctor to see if they should continue it," said Rossouw, who is acting director of the Women's Health Initiative, the unit at the National Heart, Lung, and Blood Institute (NHLBI) that conducted the study.

"If they are taking this hormone combination for short-term relief of symptoms, it may be reasonable to continue since the benefits are likely to outweigh the risks," Rossouw explained.

The trial involved 16,608 women aged 50 to 79 who still had their uterus. Such women are given a combination of estrogen and progestin, because estrogen alone can promote cancer in the lining of the uterus. The new findings do not apply to the health effects of estrogen alone, which is being looked at in a separate study by researchers at the NHLBI.

The patients were randomly assigned to receive either the estrogen/progestin combination or an inactive placebo. They were followed for an average of 5.2 years. The researchers found that although the combination hormone did reduce the risk of colon cancer and hip fractures, it also increased the risk of heart disease and breast cancer. The trial, which was to last for 8.5 years, was halted in May 2002 because of safety concerns.

The study results are scheduled to be published in the July 17th issue of The Journal of the American Medical Association, but were released early due to the importance of the findings.

The results suggest that if 10,000 postmenopausal women take estrogen plus progestin, in a given year eight more will develop invasive breast cancer, seven will have a heart attack, eight will have a stroke, and 18 more will have blood clots--including eight with blood clots in the lungs--than in a similar group of 10,000 women not taking these hormones, Rossouw noted.

"This is a relatively small annual increase in risk for an individual woman. However, even small individual risks over time, and on a population-wide basis, add up to tens of thousands of these serious adverse health events," Rossouw added.

A group of 10,000 women taking HRT in that time would experience six fewer colorectal cancers and five fewer hip fractures than women not taking HRT, the findings indicate.

Dr. Claude Lenfant, director of the NHLBI, said that menopausal women who are considering starting HRT with the hope of preventing heart disease may want to reconsider the idea.

"Menopausal women who might have been candidates for estrogen plus progestin should now focus on well-proven treatments to reduce the risk of cardiovascular disease, including measures to prevent and control high blood pressure, high blood cholesterol and obesity," he said. "Heart disease remains the number-one killer of American women."

The second trial will hopefully provide answers for women who have had a hysterectomy and are taking estrogen alone, said Dr. Marcia Stefanick, chair of the Women's Health Initiative Steering Committee. That trial is scheduled to be completed in March 2005.

"When the estrogen-only trial is completed, a comparison of the results of these two trials may provide a better idea of the roles of estrogen, compared to estrogen plus progestin, in health and disease," she said.

SOURCE: The Journal of the American Medical Association 2002;288:321-333.

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