HRT Breast Cancer Risk Greater for Slimmer Women: Study

The findings of a study by California researchers suggests that women who are thin may be at a greater risk of developing breast cancer from hormone replacement therapy (HRT) than women who are obese.  

The study was published online in the medical journal, Cancer Epidemiology, Biomarkers & Prevention. Researchers looking at the risk of breast cancer over extended periods of HRT use found that weight may play an unexplained role.

HRTs use hormones and progestins to artificially boost hormone levels in women undergoing menopause due to surgery or in postmenopausal women, to provide relief from symptoms such as hot flashes, irregular menstruation or weight gain.

Researchers from the University of Southern California looked at 2,857 cases of invasive breast cancer. They found that women who had HRT consisting of just estrogen therapy for 15 or more years had a 19% greater risk of developing breast cancer. But women who used a combined estrogen-progestin therapy, like Wyeth’s Prempro, for 15 years or more had an 83% greater risk of developing breast cancer.

The study also unveiled another correlation. Women who had a body mass index (BMI) less than 30 showed increased risk of breast cancer the longer they took any form of HRT. However, women with a BMI of 30 or more, considered obese, showed no increased breast cancer risk over time.

The study comes as a Philadelphia court weighs a Prempro HRT lawsuit brought against Pfizer and its Wyeth unit by two women, Sharon Buxley and Joy Henry. Buxley, 66, and Henry, 75, both claim that the side effects of Prempro caused them to develop breast cancer. The trial is expected to last throughout the month and potentially well into September.

Prempro is an HRT that contains a combination of the drugs Provera and Premarin. The drug was originally developed by Wyeth, which was acquired by Pfizer last year.

In 2002 the National Institutes of Health released the results of studies that found women receiving HRT were at higher risk of breast cancer, strokes and heart attacks. The studies, part of the Women’s Health Initiative, sparked most of the hormone replacement therapy breast cancer lawsuits currently pending throughout the country.

There are about 9,000 Prempro lawsuits pending against Pfizer’s Wyeth unit by women who claim that they developed breast cancer from the hormone replacement therapy. The cases allege that the drug maker intentionally hid the risk of breast cancer from women. As a result of Wyeth’s conduct, punitive damages have been awarded in several cases where juries saw the drug maker’s behavior as reckless disregard for the risk of injury to consumers.