Breast cancer reduction findings need further investigation

Last month, an observational study conducted by the Women’s Health Initiative (WHI) was halted prematurely because of possible risks associated with the use of conjugated equine estrogen (CEE) therapy in women who have undergone hysterectomy.

The National Institutes of Health (NIH) determined from reviewing the study data that long-term CEE use could increase the risk of stroke in otherwise healthy women. While observations from the WHI study included a reported decrease of 23 percent in risk for invasive breast cancer in the women taking CEE compared to the women taking a placebo, this was not the main focus of the study and the Susan G. Komen Breast Cancer Foundation cautions that the data should be studied further.

The main goal of the study was to evaluate the risk for coronary heart disease (CHD) in post-menopausal women ages 50–79 who had undergone a hysterectomy and who were taking CEE alone. Study results indicate CEE use produced no overall benefit in lowering the risk for coronary heart disease. This discovery, combined with the increased risk of stroke, caused the NIH to halt the study early. Women enrolled in theWHI study represent multiple ethnic groups and the average duration for use of CEE among the participants was 6.8 years.

News of the study’s halt was reported in the April 14, 2004, issue of The Journal of the American Medical Association. Another arm of the WHI investigating health risks associated with post-menopausal hormone therapy was also shut down prematurely in 2002, after it was found that long-term use of a progestin and estrogen combination produced an unacceptable risk of invasive breast cancer in otherwise healthy post-menopausal women.

Since the halting of that study arm, product packages have been re-labeled to warn of the increased risk of strokes, heart attacks, blood clots and breast cancer associated with estrogen-progestin therapy. Post-menopausal patients who use such hormone therapy are now urged by the U.S. Food and Drug Administration (FDA) and most physicians to consider the approach as a short-term option for the relief of menopausal symptoms, such as hot flashes.

“We now anticipate that the labeling of the estrogen-only products will be reviewed in the wake of these most recent WHI findings,” said Cheryl Perkins, M.D., senior clinical advisor for the Komen Foundation. “Postmenopausal women, following the advice of their physicians, should consider using CEE therapy only for menopausal symptoms at the smallest effective dose and for the shortest possible time.”

Dr. Perkins, who is also a breast cancer survivor, concluded: “The more we can learn about those factors that either increase or reduce a woman’s risk of breast cancer, the more we can empower women in the fight against a disease that often leaves them feeling powerless.”