Wednesday, February 24, 2010 (Last Updated: 02/25/2010)
WEDNESDAY, Feb. 24 (HealthDay News) -- The nonsteroidal selective estrogen-receptor modulator lasofoxifene may reduce the risk of fractures, stroke, estrogen receptor (ER)-positive breast cancer, and coronary heart disease in postmenopausal women with osteoporosis. However, the drug significantly increases the risk of venous thromboembolic events, according to a study in the Feb. 25 issue of the New England Journal of Medicine.
Steven R. Cummings, M.D., of the University of California in San Francisco, and colleagues in the Postmenopausal Evaluation and Risk Reduction with Lasofoxifene (PEARL) trial randomized 8,556 women with a bone mineral density T score of −2.5 or less to daily treatment with 0.25 or 0.5 mg lasofoxifene or placebo for five years. Study end points included vertebrae and non-vertebrae fractures, ER-positive breast cancer, coronary heart disease, and stroke.
Compared to placebo, the researchers found that the lasofoxifene 0.5- and 0.25-mg groups had lower risks for vertebrae fractures (odds ratios, 0.58 and 0.69, respectively) and stroke (odds ratios, 0.64 and 0.61, respectively). The 0.5-mg group also had lower risk for non-vertebrae fractures (odds ratio, 0.76), ER-positive breast cancer (odds ratio, 0.19), and coronary heart disease events (odds ratio, 0.68). However, the 0.25- and 0.5-mg doses had higher risks for venous thromboembolism than placebo (odds ratios, 2.67 and 2.06, respectively).
"Similar to estrogen and other selective estrogen-receptor modulators, lasofoxifene more than doubled the relative risk of venous thromboembolic events and pulmonary embolism, although the increase in absolute risk was very small," writes the author of an accompanying editorial.
The study was supported by Pfizer. Several authors reported financial relationships with pharmaceutical companies. Three of the study authors also hold patents related to lasofoxifene.
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