Lasofoxifene in Postmenopausal Women with Osteoporosis

Background The effects of lasofoxifene on the risk of fractures, breast cancer, and cardiovascular disease are uncertain. Methods In this randomized trial, we assigned 8556 women who were between the ages of 59 and 80 years and had a bone mineral density T score of –2.5 or less at the femoral neck or spine to receive once-daily lasofoxifene (at a dose of either 0.25 mg or 0.5 mg) or placebo for 5 years. Primary end points were vertebral fractures, estrogen receptor (ER)–positive breast cancer, and nonvertebral fractures; secondary end points included major coronary heart disease events and stroke. Results Lasofoxifene at a dose of 0.5 mg per day, as compared with placebo, was associated with reduced risks of vertebral fracture (13.1 cases vs. 22.4 cases per 1000 person-years; hazard ratio, 0.58; 95% confidence interval [CI], 0.47 to 0.70), nonvertebral fracture (18.7 vs. 24.5 cases per 1000 person-years; hazard ratio, 0.76; 95% CI, 0.64 to 0.91), ER-positive breast cancer (0.3 vs. 1.7 cases per 1000 perso...