AIM: To study the efficacy and safety of abiraterone in patients with and without prior chemotherapy.METHODS: The databases including Pub Med and abstracts presented at the American Society of Clinical Oncology meetings up to April 2014 were systematically searched. Eligible studies included randomized controlled trials(RCTs) in which abiraterone plus prednisone was compared to placebo plus prednisone in metastatic castration-resistant prostate cancer(CRPC) patients. The summary incidence, relative risk, hazard ratio and 95%CI were calculated using random or fixed-effects models. Heterogeneity test was performed to test between-study differences in efficacy and toxicity.RESULTS: A total of two phase III RCTs were included in our analysis, with metastatic CPRC patients before(n = 1088) and after chemotherapy(n = 1195). Prior chemotherapy did not significantly alter the effect of abiraterone on overall survival(P = 0.92) and prostatespecific antigen(PSA) progression-free survival(P = 0.13), but reduced its effect on radiographic-prog-ression-free survival(P = 0.04), objective response rate(P < 0.001), and PSA response rate(P < 0.001). Prior chemotherapy significantly increased the specific risk of fluid retention and edema(P < 0.001) and hypokalemia(P < 0.001), but decreased the risk of all-grade hypertension(P < 0.001) attributable to abiraterone. There was no significant difference of cardiac disorders associated with abiraterone between the two settings(P = 0.58). CONCLUSION: Prior chemotherapy may reduce the effectiveness of abiraterone in patients with metastatic CRPC. AIM: To study the efficacy and safety of abiraterone in patients with and without prior chemotherapy. METHODS: The databases including Pub Med and abstracts presented at the American Society of Clinical Oncology meetings up to April 2014 were systematically searched. Eligible studies included randomized controlled trials The summary incidence, relative risk, hazard ratio and 95% CI were calculated using random or fixed-effects models. Heterogeneity (RCTs) in which abiraterone plus prednisone was compared to placebo plus prednisone in metastatic castration-resistant prostate cancer (CRPC) patients. Results were tested to test between-study differences in efficacy and toxicity. A total of two phase III RCTs were included in our analysis, with metastatic CPRC patients before (n = 1088) and after chemotherapy (n = 1195). did not significantly alter the effect of abiraterone on overall survival (P = 0.92) and prostatespecific antigen (PSA) progression-free survival 3), but reduced its effect on radiographic-prog-ression-free survival (P = 0.04), objective response rate (P <0.001), and PSA response rate there was no significant difference of cardiac disorders associated with abiraterone between the two settings (P <0.001) and hypokalemia (P <0.001), but decreased the risk of all-grade hypertension P = 0.58). CONCLUSION: Prior chemotherapy may reduce the effectiveness of abiraterone in patients with metastatic CRPC.