Major study shows women on combined hormone therapy likelier to die from breast cancer

Study published today shows risk of long-term combined hormone therapy

SAN ANTONIO (Oct. 19, 2010) — Taking combined hormone replacement therapy over a long period of time not only increases the risk of developing breast cancer, but also doubles the risk of dying from it, according to a large study published today in the Journal of the American Medical Association.

Two researchers at The University of Texas Health Science Center at San Antonio contributed to the Women’s Health Initiative study published today. The paper shows that the study’s initial results, released seven years ago, potentially have saved thousands of women’s lives.

“It’s an important finding – very important for physicians when counseling their patients,” said Robert S. Schenken, M.D., professor and chairman of obstetrics and gynecology at the Health Science Center.

In the study, 16,608 postmenopausal women were randomized between placebo and a commonly used hormone combination of estrogen and progestin, with Dr. Schenken leading the San Antonio team, a major site for the study.

Initial results, published in 2003, showed that taking the combination therapy for a long period of time increased the risk of getting breast cancer by 25 percent.

Over the year following the publication of these results, most women stopped taking combined therapy. Peter Ravdin, M.D., Ph.D., director of the Breast Health Clinic at the Health Science Center’s Cancer Therapy & Research Center (CTRC), showed that this resulted in a sudden 10 percent drop-off in new breast cancer cases in the United States, breaking the 20-year-long trend in increasing risk. That means about 17,000 fewer women per year are getting breast cancer.

“This study questioned conventional wisdom,” Dr. Ravdin said, “and found an unexpected result that was very useful.”

Dr. Ravdin, who was working at The University of Texas MD Anderson Cancer Center in 2003 but returned to the CTRC earlier this year, said some in the medical community initially responded with skepticism, contending that cases caused by the combined therapy were more benign cancers.

But the long-term follow-up of this study shows that the women who were taking this form of hormonal therapy not only had an increased risk of developing breast cancer, Dr. Ravdin said, but developed deadlier forms of breast cancer, doubling their risk of dying from it.

“We all should salute all the women who participated in this study and leaders like Dr. Schenken, who bravely saw that this study, at a time when many people thought all hormonal therapies were safe, was completed,” Dr. Ravdin said. “Their work is saving thousands of lives per year.”

The University of Texas Health Science Center at San Antonio, one of the country’s leading health sciences universities, ranks in the top 3 percent of all institutions worldwide receiving National Institutes of Health (NIH) funding. Research and other sponsored program activity totaled a record $259 million in fiscal year 2009. The university’s schools of medicine, nursing, dentistry, health professions and graduate biomedical sciences have produced approximately 26,000 graduates. The $739 million operating budget supports eight campuses in San Antonio, Laredo, Harlingen and Edinburg. For more information on the many ways “We make lives better®,” visit

The Cancer Therapy & Research Center (CTRC) at The University of Texas Health Science Center at San Antonio is one of the elite academic cancer centers in the country to be named a National Cancer Institute (NCI) Designated Cancer Center, and is one of only four in Texas. A leader in developing new drugs to treat cancer, the CTRC Institute for Drug Development (IDD) conducts one of the largest oncology Phase I clinical drug programs in the world, and participates in development of cancer drugs approved by the U.S. Food & Drug Administration. For more information, visit

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