Hormone Therapy Side Effects Linked to Breast Cancer Risk: Study

The findings of a new study appear to indicate that long-term use of any estrogen hormones for treatment of menopause may increase the risk of breast cancer. 

Research presented at the conference for the American Association for Cancer Research in Chicago, appears to confirm previous concerns that side effects of hormone replacement therapy (HRT), which combines estrogen and progestin, can increase the breast cancer risk.

The study was funded by the National Cancer Institute, and contradicts the findings of a study published in January, which was funded by the drug maker Wyeth. That research cast doubts on the links between hormone therapy and cancer.

The lastest research involved data from the Nurse’s Health Study, finding an 88% increase in the risk of breast cancer for women who underwent HRT over a period of 10-15 years. The risk doubled if the women used HRT for 15 to 20 years.

In recent years, Wyeth, which is a division of Pfizer, has been the subject of numerous lawsuits and multi-million dollar verdicts for women who say that the company’s HRT drug causes breast cancer. Most of the complaints were filed after a 2002 study by the National Institutes of Health found that women receiving HRT were at a higher risk of breast cancer, strokes and heart attacks.

About 10,000 lawsuits have been filed by consumers over Prempro, which contains a combination of the drugs Provera and Premarin to artificially boost hormone levels in women undergoing menopause due to surery or in postmenopausal women. The suits allege that Wyeth failed to adequately research the hormone therapy side effects or warn that the medication may increase the risk of breast cancer.

Following several trials that resulted in multi-million dollar compensatory awards and even larger punitive damage awards after juries found that Wyeth intentionally hid the risk of breast cancer from Prempro, the drug maker indicated in December that nearly half of all Prempro breast cancer lawsuits have been settled.