July 9, 2002
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Hormone trial halted early due to boost in breast cancer risk

SEATTLE -- July 9, 2002 (Cancer Digest) -- One of the major health questions women face in their lives has been answered as researchers nationwide have halted early part of a 40-center study of hormone replacement therapy for menopause after finding an increased risk of breast cancer.

The large 12-year trial, a component of the Women's Health Initiative (WHI), which had been scheduled to continue until 2005, also found increases in coronary heart disease, stroke, and pulmonary embolism in study participants on estrogen plus progestin compared to women taking placebo pills.

Dr. Garnet Anderson, a biostatistician who led the data analysis for the trial at the Fred Hutchinson Cancer Research Center, Seattle, Washington said the study was designed to stop at the earliest sign of adverse effects.

"Because breast cancer is so serious an event, we set the bar lower to monitor for it. We pre-specified that the change in cancer rates did not have to be that large to warrant stopping the trial. And the trial was stopped at the first clear indication of increased risk," she said.

Dr. Gerardo Heiss, professor of epidemiology at the University of North Carolina at Chapel Hill School of Public Health, and one of the investigators on the trial said the data clearly showed the risks outweigh the benefits.

"This was a randomized, placebo-controlled trial of estrogen plus progestin in more than 16,000 women with a uterus," Heiss said in a prepared statement. "The estrogen plus progestin trial was stopped early -- after 5.2 years -- because of a 26 percent increased risk for breast cancer and also a lack of overall benefit. As soon as the increased risk for breast cancer was established, the independent data and safety monitoring board halted the study."

The report from the WHI investigators on the estrogen plus progestin study findings will be published in the July 17 issue of the Journal of the American Medical Association. Because of the importance of the information, the study was released today, July 9, as an expedited article on the JAMA Web site. (Full text version available to all at www.jama.com.)

The study, funded by the National Heart Lung and Blood Institute, is part of the 12-year, 40-center Women's Health Initiative (WHI) involving 160,000 women taking part in a three-component randomized hormone replacement clinical trial, or an observational study, or a community prevention study. It is the largest study of women's health ever undertaken in the United States.

There were noteworthy benefits of estrogen plus progestin, including fewer cases of hip fractures and colon cancer, but on balance the researchers said the harm was greater than the benefit.

"We wish to express our appreciation and thanks to the 16,608 women who participated in this WHI study," Heiss said. "They are true pioneers and have made an important contribution in answering a very important question for millions of women.

"Because of them, we now know the balance of risks and benefits of the estrogen plus progestin treatment most commonly prescribed in the United States for postmenopausal women who have a uterus," he said. "The bottom line is that estrogen plus progestin is not a viable option to prevent chronic disease."

A separate WHI study of estrogen alone in women who had a hysterectomy before joining the WHI hormone program continues unchanged because, at this point, the balance of risks and benefits of estrogen alone is still uncertain.

About 6 million women in the U.S. are taking estrogen plus progestin for a variety of reasons, including symptom relief, because their doctors advised it, or for long-term health.

"Women with a uterus who are currently taking estrogen plus progestin should have a serious talk with their doctors to see if they should continue it," said Dr. Jacques Rossouw, acting director of the WHI. "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. Longer term use or use for disease prevention must be re-evaluated given the multiple adverse effects noted in WHI."

NHLBI Director Dr. Claude Lenfant, says the results will likely change clinical practice.

"We have long sought the answer to the question: Does postmenopausal hormone therapy prevent heart disease and, if it does, what are the risks," he said. "The bottom-line answer from WHI is that this combined form of hormone therapy is unlikely to benefit the heart. The cardiovascular and cancer risks of estrogen plus progestin outweigh any benefits - and a 26 percent increase in breast cancer risk is too high a price to pay, even if there were a heart benefit. Similarly, the risks outweigh the benefits of fewer hip fractures."