Comparison Between Alendronate and Denosumab in Preventing Bone Loss and Lowering Fracture Risk Related to Adjuvant Endocrine Therapy for Breast Cancer: Real-World Data From a Third-Level Center Experience.

Objective: Adjuvant endocrine therapy (AET) for breast cancer treatment is associated with bone loss and increased fracture risk. This study evaluated variations in bone mineral density (BMD), trabecular bone score (TBS), biochemical parameters, and incidence of major fractures in a population of postmenopausal women on AET comparing denosumab 60 mg subcutaneously every 6 months and alendronate 70 mg orally every week.

Methods: After propensity score matching, a population of postmenopausal women on AET was retrospectively evaluated comparing effects on BMD, TBS, bone turnover markers, and major fracture incidence (assessed by quantitative vertebral morphometry) after a nearly 3-year follow-up of denosumab 60 mg subcutaneously every 6 months and alendronate 70 mg orally every week (n = 286; ratio, 1:1).

Results: The denosumab group showed a higher increase in total hip BMD (+0.034 g/cm vs +0.002 g/cm, P < .01), femoral neck BMD (+0.014 vs 0.000 g/cm, P < .01), lumbar spine BMD (+0.053 vs +0.005 g/cm, P < .01), and TBS (+0.017 vs -0.027, P < .01) than the alendronate group. Treatment with denosumab was associated with a 66% risk reduction in major fractures compared with alendronate (odds ratio, 0.34; P < .01). There was no significant difference between groups in reducing fracture risk considering only patients with normal BMD at baseline.

Conclusion: Treatment with denosumab during AET improves BMD and TBS more than alendronate and is associated with a higher reduction in major fractures in postmenopausal patients affected by osteopenia or osteoporosis.