The risk of fragility fractures in men with prostate cancer treated with androgen deprivation therapy

Summary: Androgen Deprivation Therapy (ADT) increases long-term fracture risk in prostate cancer. Our study showed a higher fracture risk within six months of ADT use, and current use was associated with a higher risk of fragility fractures. Attention is needed for the prevention of fragility fractures at the start of ADT. Purpose: Androgen Deprivation Therapy (ADT) is known to increase long-term fracture risk in men with prostate cancer (PCa), although the risk of fragility fractures remains unclear. This study aims to evaluate the risk of fragility and malignancy-related fractures in men with PCa treated with ADT. Methods: We conducted a retrospective cohort study of men with PCa. Follow-up time was divided into 30-day intervals and exposure (current, past, or no-ADT use). Current ADT use was stratified by duration of ADT use (≤ 182 days, 183–730 days, and > 730 days). Cause-specific Cox proportional hazard models were used to estimate the risk of fractures. Results: We included 471 patients (mean age 70.5 (± 8.3) years). The mean follow-up time was 5.0 (± 1.7) years in patients who never started ADT, 3.4 (± 2.3) years and 4.1 (± 2.0) years in patients who started ADT at baseline and during follow-up, respectively. In total, 60 patients had a fracture, 48 (80%) fragility, and 12 (20%) malignancy-related fractures. Current ADT use was associated with a higher risk of all fractures (HR 5.10, 95% CI 2.34–11.13) and fragility fractures (HR 3.61, 95% CI 1.57–8.30). The association with malignancy-related fractures could not be studied due to no events during no-ADT use. There was an increased risk of all fractures with longer duration of ADT use. Conclusions: Current ADT use was associated with a higher risk of fragility fractures than no-ADT use. A higher fracture risk was observed within the first six months of ADT use and persisted for longer durations.