The effect of exemestane on bone mineral density during the first 3 years of adjuvant treatment of postmenopausal women with early breast cancer.

Abstract

e11045 Background: Adjuvant therapy with aromatase inhibitors (AI) is associated with increased bone loss in postmenopausal women. We assessed changes in bone mineral density (BMD) from baseline to 36 months of treatment in patients receiving exemestane (EXE) as initial adjuvant therapy with/without oral bisphosphonates (Bis). Methods: Postmenopausal women with endocrine responsive breast cancer receiving EXE as adjuvant therapy at our hospital since 2004 were enrolled in this study. BMD was assessed by dual-energy X-ray absorptiometry at baseline and after 6, 12, 24 and 36 months. Oral Bis (risedronate or alendronate) treatment was initiated when patients were diagnosed as having osteoporosis with a T-score of -2.5 or lower. Results: Seventy-six patients were enrolled in the study between 2004 and 2009. Patients' median age was 67 years and the median follow-up period was 537.5 days. Thirty-two patients were administered Bis (risedronate in 19 patients, alendronate in 13 patients). Within 6 months of hormone therapy, BMD increased by 2.7% from baseline at the lumbar spine and BMD decreased by 0.6% at the femoral neck. However, BMD increased by 2.9% at the lumbar spine and 1.6% at the femoral neck for 3 years of treatment. In patients treated with upfront Bis (n = 19), 5.1% BMD increase from baseline was noted at the lumbar spine whereas in those without Bis (n = 34) BMD decrease by 1.3% from baseline within 12 months (p = 0.0214). Fractures were observed in 5 patients (6.6%), and 4 patients (5.3%) had fragility fractures. Conclusions: Oral Bis prevented EXE-induced bone loss, and upfront treatment of Bis significantly increased BMD at the lumbar spine. No significant financial relationships to disclose.