Effect of bisphosphonates on overall survival in subgroups of patients with prostate cancer

Adjuvant therapy with bisphosphonates in prostate cancer is effective in improving bone mineral density and thus reducing fractures and skeletal-related events. We analyzed the effect of bisphosphonates on overall survival (OS) in subgroups of patients with prostate cancer. A systematic literature search was conducted of the PubMed database and the bibliographies of related studies. The long-term OS rates were extracted from every eligible trial. The hazard ratio (HR) was pooled with the fixed effects model, and preplanned subgroup analyses were performed. The search yielded 112 articles, of which 10 articles with 13 patient subgroups met the eligibility criteria. The meta-analysis of all 13 subgroups showed that adjuvant bisphosphonate therapy did not significantly improve OS versus the control group (HR = 0.961, 95% CI 0.899-1.026, p = 0.233) with low heterogeneity (I² = 13.47%, degrees of freedom = 12, p = 0.336). There was no significant improvement in OS with the addition of bisphosphonates in the major subgroup analyses (metastatic (M1) versus non-metastatic, clodronate versus zoledronic acid, castration-sensitive prostate cancer (CSPC) versus castration-refractory prostate cancer). When the subgroups were further divided, adjuvant bisphosphonate therapy significantly improved OS in patients with CSPC + M1 (HR = 0.874, 95% CI 0.778-0.982, p = 0.023; I² = 0.0%, degrees of freedom = 3, p = 0.579). Our study demonstrated that bisphosphonates do not significantly improve long-term OS in patients with prostate cancer. However, adjuvant bisphosphonate therapy significantly improves OS in the subgroup of patients with CSPC + M1.