Calculate Your Risk: Hormones Versus Breast Cancer

CBS Health Watch - August 2001

Introduction

Soon after her 50th birthday, nurse Joan Shaw began to wake up each night,her nightgown drenched in sweat. Often, she would be unable to fall back to sleep. Having just entered menopause, she began taking a combination of the hormones estrogen and progestin. Despite the risks of possible side effects,Shaw has been taking the hormones for 6 years.

Her decision to take HRT was agonizing because she had to consider conflicting safety information. New research has made this decision even more complicated for menopausal women. According to two studies (one in the January 26, 2000 issue of the Journal of the American Medical Association and the other in the February 16, 2000 issue of the Journal of the National Cancer Institute) women who choose HRT may run a significantly higher risk for breast cancer than was previously suspected.

Decision More Complicated

Researchers at the University of Southern California (USC) and the National Cancer Institute (NCI) independently determined that taking anestrogen/progestin combination packed a significantly higher risk of side effects than taking estrogen alone. (Estrogen taken alone has been linked to a greater risk of uterine cancer. Progestin was added to the mix to protect the uterus from malignancy.) An estimated 8.6 million women in the United States use this combined hormone therapy.

The USC study calculated that for every 5 years a woman takes estrogen, her risk of breast cancer goes up 6%. But for every 5 years that she uses the more commonplace combination of estrogen and progestin, her risk jumps 24%.NCI researchers estimated the risk of taking the combination to be 8% a year, as opposed to 1% for women who take only estrogen. Lean women were most at risk.

NCI epidemiologist Catherine Schairer, lead author of the NCI study,translated these percentages to mean that for every 100,000 women taking HRT, approximately 350 develop breast cancer. Among lean women taking estrogen for 5 years, the number rises to 400, and using combined hormone therapy raises the incidence to 560 cases. "But the good news is that risk diminishes within 4 or 5 years of stopping treatment," says Dr. Schairer. Meanwhile, many are anxiously awaiting the results of a clinical trial gauging the risks and benefits of estrogen-progestin therapy. Launched in 1993 by the Women's Health Collective, the study involves nearly 30,000 women aged 50 to 79. But results are not expected until 2005. [Your decision to use synthetic estrogen and synthetic progestins should be carefully considered).

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