Arimidex Bone Mass Index and Oral Bisphosphonates (ARBI)

To investigate the management of bone health in postmenopausal women with early breast cancer (BCA) scheduled to receive anastrozole. Postmenopausal women with hormone receptor-positive early BCA are assigned to 1 of 3 strata depending on their pre-existing risk of fragility fracture. Patients (pts) with a bone mineral density (BMD) T-score <-2.0 for either spine or hip are designated higher-risk (H) for fracture and receive anastrozole 1 mg/day plus risedronate orally. Moderate-risk (M) pts (T-score <-1.0 for spine or hip but -2.0 at both sites) are randomized to receive anastrozole plus risedronate (A+R) or anastrozole alone. Pts with T-scores -1.0 at both spine and hip were designated lower-risk (L) and receive anastrozole alone. All pts receive calcium and vitamin D. Lumbar spine and total hip BMD are assessed at baseline, 12, and 24 months.