Prempro Doubles Breast Cancer Death Risk, Study FindsOct 20, 2010 | Parker Waichman LLP
Prempro, already associated with a higher risk of breast cancer, has now been found to double the risk of death from the disease. Pfizer Inc.’s Prempro was once given to millions of women to treat the symptoms of menopause.
Prempro is a combination of the hormones estrogen and progestin. In 2002, the Women’s Health Initiative (WHI), a major study conducted by the National Institutes of Health (NIH), determined that Prempro and similar drugs significantly increased the risk of stroke, blood clots, heart attacks and breast cancer. The results were so alarming that the NIH canceled the study, citing risk to the study’s participants.
The authors of the early study also suggested that many of the women who used the medications should quit and talk to their doctors about alternatives. According to a Bloomberg News report, the decline in hormone use after the WHI results were initially released led to a drop in breast cancer rates, with about 100,000 fewer invasive tumors detected from 2002 to 2007 than expected.
The Prempro label now advises that the drug should be used at the lowest effective dose and for the shortest duration possible.
The latest breast cancer study also comes from the WHI, and is published in the Journal of the American Medical Association. The new study tracked 12,788 women for almost 8 years after the WHI trial was stopped and found 678 cases of invasive breast cancer, including 385 for women treated with estrogen plus progestin therapy, and 293 with a placebo. Investigators calculated there were 2.6 deaths caused by breast cancer for every 10,000 women taking hormones each year, compared with 1.3 deaths for those on a placebo.
“More women died of breast cancer in the combined hormone therapy group compared with the placebo group (25 deaths [0.03 percent per year] vs. 12 deaths [0.01 percent per year]), representing 2.6 vs. 1.3 deaths per 10,000 women per year, respectively,” the authors write. “Consideration of all-cause mortality after breast cancer diagnosis provided similar results; among women in the combined hormone therapy group, there were 51 deaths (0.05 percent per year) compared with 31 deaths (0.03 percent per year) among women in the placebo group, representing 5.3 vs. 3.4 deaths per 10,000 women per year, respectively.”
According to an editorial that accompanied the new study, it is likely that the risk of dying from breast cancer was underestimated and will increase with time. The author of the editorial called for more studies to determine if treatment with hormone therapy over a brief time is safe, as many doctors believe.
“Given the substantial population of women who seek relief from menopausal symptoms and the large potential burden of disease that could be created if medications given to alleviate symptoms today cause cancer and other deaths tomorrow, it seems that additional randomized trials are needed,” the editorial stated.