Preventive effect of risedronate on bone loss and frailty fractures in elderly women treated with anastrozole for early breast cancer

The aim of this study was to assess the effect of adjuvant anastrozole, alone or associated with risedronate, on BMD and bone fracture risk in women more than 70 years old with hormone receptor-positive early breast cancer (EBC). In a group of 51 elderly women (aged 76.4 ± 5.0 years) considered for adjuvant aromatase inhibitors for EBC, 24 patients with T-scores ≥ −2 and no prevalent fractures received anastrozole 1 mg/day (group A), and 27 patients with T-scores < −2, or with T-scores ≥ −2 and prevalent fractures (group B), received anastrozole (1 mg/day) plus risedronate (35 mg/week). Both groups received supplementation with 1 g calcium carbonate and 800 IU vitamin D per day. Differences in BMD and frailty fractures were evaluated after 1 and 2 years. In group A, significant decreases in BMD were observed in the lumbar spine (Δ BMD, −0.030 ± 0.04 g/cm², P < 0.05), femoral neck (Δ BMD, −0.029 ± 0.05 g/cm², P < 0.05), and trochanter (Δ BMD, −0.026 ± 0.03 g/cm², P < 0.01) after 2 years. The greatest percent reduction in height (Hpr) emerged in the thoracic spine (3.6 ± 2.4%, P < 0.01), although only one incident vertebral fracture was observed. In group B, BMD increased in the lumbar spine (Δ BMD, 0.038 ± 0.04, P < 0.001), although no significant changes were seen in the hip regions. The decline in Hpr was negligible (about 1%). No incident fractures were observed at follow-up. In conclusion, anastrozole treatment for EBC in elderly women seems to have only mild negative effects on the femoral bone. Risedronate makes the use of anastrozole safer, even for osteopenic or osteoporotic elderly patients.