Background: PARP inhibitors effectively treat several solid tumors, regardless of the presence of BRCA mutations. Patients with castration-resistant metastatic prostate cancer become refractory to androgen deprivation therapy. PARP inhibitors were recently approved for use in prostate cancer, and have opened new avenues in prostate cancer treatment research. Methods: We systematically searched multiple databases using pre-specified search terms. We included only phase III RCTs comparing PARP inhibitors versus standard of care in patients with castration-resistant biopsy-proven metastatic prostate cancer. The outcomes studied were radiologically guided progression-free survival (PFS) and overall survival (OS). We used a random effects model via RevMan 5.4 software for statistical analysis. Results: 3 phase III RCTs met the inclusion criteria with a total of 1606 patients (PARP inhibitors = 867 patients, standard of care = 739 patients). Compared to the standard of care, PARP inhibitors showed significantly higher PFS [HR = 0.62( 95% CI, 0.49-0.78) P < 0.0001]. There was no statistically significant difference in OS [HR = 0.85( 95% CI, 0.69-0.1.04) P = 0.11] between the two groups. Conclusions: The use of PARP inhibitors in patients with castration-resistant metastatic prostate cancer is associated with improved progression-free survival. No significant difference was observed in overall survival between the two groups. There is a need to study the cost-benefit analysis of using PARP inhibitors as they do not show any improvement in overall survival.

E = Exposure group (PARP inhibitors) C = Control group.