Effect of Raloxifene on Bone Mineral Density in Premenopausal Women at Increased Risk of Breast Cancer

Abstract

Raloxifene is a promising breast cancer prevention agent in postmenopausal women at increased risk for breast cancer. The effects of raloxifene in premenopausal women are unknown. We evaluated the effect of raloxifene in premenopausal women at increased risk for breast cancer on bone mineral density (BMD). This was a phase II clinical trial. This study was conducted at an academic medical center. Thirty-seven premenopausal women at increased risk for breast cancer enrolled in the trial. Thirty subjects began treatment and 27 were evaluable. Raloxifene (60 mg daily) and elemental calcium (500 mg daily) were given for 2 yr. Subjects were followed up off medications for 1 yr. The primary end point was the intrasubject percent change in BMD at 1 yr measured by dual-energy x-ray absorptiometry. The mean baseline lumbar spine density was 1.027 g/cm(2). Lumbar spine density decreased 2.3% at 1 yr (P < 0.00001) and 3.5% at 2 yr (P < .00001). Percent change from yr 2 to 3 was +1.4%. The mean baseline total hip bone density was 0.905 g/cm(2). Total hip density decreased 0.3% at 1 yr and 1.0% at 2 yr (P = 0.033). Percent change from yr 2 to 3 was +1.7%. Raloxifene use is associated with a decrease in BMD in premenopausal women at increased risk for breast cancer. The clinical significance of this decrease is unknown and is attenuated with stopping raloxifene.