Risk of osteoporosis and fracture among patients with breast cancer: a systematic review and meta-analysis of cohort studies.

BACKGROUND: Breast cancer survivors may be at increased risk of osteoporosis and fractures because of disease-related factors and treatment-induced bone loss. However, the available evidence remains inconsistent. This study aimed to evaluate the associations between breast cancer and the risks of osteoporosis and fracture through a systematic review and meta-analysis. METHODS: PubMed, Embase, Web of Science, and the Cochrane Library were systematically searched from database inception to May 1, 2026. Cohort studies investigating the associations between breast cancer and the risks of osteoporosis or fracture were included. Hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) were pooled using random-effects models. Subgroup analyses were performed according to age and treatment modality. RESULTS: A total of 16 cohort studies were included in this meta-analysis. The pooled analysis demonstrated that breast cancer was associated with significantly increased risks of osteoporosis (HR = 1.54, 95% CI: 1.13-2.09) and fracture (HR = 1.49, 95% CI: 1.03-2.16). Age-stratified findings suggested comparable osteoporosis risks between women aged <50 years and those aged ≥50 years. In the treatment subgroup analysis, aromatase inhibitor therapy was associated with a significantly increased risk of osteoporosis (HR = 1.65, 95% CI: 1.05-2.60), whereas no significant associations were observed among tamoxifen users or patients receiving chemotherapy. CONCLUSION: Breast cancer is significantly associated with increased risks of both osteoporosis and fracture. Aromatase inhibitor therapy may further contribute to osteoporosis risk. These findings highlight the importance of bone health monitoring and fracture prevention strategies in breast cancer survivors. SYSTEMATIC REVIEW REGISTRATION: https://www.crd.york.ac.uk/PROSPERO/view/CRD420261419796, identifier CRD420261419796.