Japanese cancer survivors have a higher risk of fragility fractures over ten years.

This study aimed to clarify the risk of fragility fractures (FFs) in Japanese cancer survivors compared with individuals without cancer by incorporating time-dependent variables. In a 10-year cohort of 10,330 adults aged 40–69 years, we assessed the risk of FFs (i.e., hip, vertebral compression, and distal radius fractures) associated with cancer status by using time-dependent Cox proportional hazards analyses. The models were adjusted for demographic, lifestyle, and medical factors. The time-dependent variables included cancer status and age. Analyses were performed according to cancer treatment status, number of primary cancers, and cancer site. Among the 10,330 participants (mean age, 56.4 years; females, 6148), 386 experienced FFs. Compared with participants without cancer, a higher risk of overall FFs was observed in participants with cancer (hazard ratio [HR], 1.40; 95% confidence interval [CI], 1.03–1.89). This risk was further elevated among participants with active cancer (HR, 1.71; 95% CI, 1.15–2.55), multiple primary cancers (HR, 1.42; 95% CI, 1.04–1.95), stomach cancer (HR, 1.84; 95% CI, 1.01–3.37), kidney cancer (HR, 3.74; 95% CI, 1.20–11.70), and hematologic cancer (HR, 7.70; 95% CI, 2.45–24.16). These findings highlight the importance of FF prevention strategies in cancer survivorship care in aging Asian populations.