Outcomes with Abiraterone Acetate in Metastatic Castration-resistant Prostate Cancer Patients Who Have Poor Performance Status

Background: Although abiraterone acetate ( abiraterone) has proven efficacy in two randomised phase 3 trials in metastatic castration- resistant prostate cancer ( mCRPC), patients who had an Eastern Cooperative Oncology Group ( ECOG) performance status ( PS) 2 were either excluded or under- represented in these trials. Objective: To compare outcomes in ECOG PS 0- 1 and 2 in mCRPC patients treated with abiraterone. Design, setting, and participants: Cancer registries from three Canadian centres were used to retrospectively identify mCRPC patients ( postdocetaxel and docetaxel- nai " ve) treated with abiraterone. ECOG PS, clinicopathologic characteristics, prostate- specific antigen ( PSA) response, and survival data were collected. Outcome measurements and statistical analysis: Survival outcomes were estimated using the Kaplan- Meier method and compared using the log- rank test. Cox proportional hazards modelling was used to examine the effect of clinicopathologic characteristics on overall survival ( OS) and time to PSA progression. Results and limitations: A total of 519 patients were identified; 61% ( n = 318) and 39% ( n = 201) were ECOG PS 0- 1 and 2, respectively. ECOG PS 0- 1 patients were significantly more likely than PS 2 patients to achieve a PSA decline 50% from baseline ( 45% vs 32%; p = 0.003, Fisher exact test) and had significantly longer median time to PSA progression ( 5.2 mo vs 4.1 mo; p = 0.023), median treatment duration ( 7.4 mo vs 4.5 mo; p < 0.001), and median OS ( 20.0 mo vs 9.1 mo; p < 0.001). On multivariate analysis, ECOG PS was a significant factor for OS ( p < 0.001), time to PSA progression ( p = 0.043), and PSA decline ( p = 0.002). Potential limitations include the retrospective study design and subjective nature of ECOG PS classification. Conclusions: ECOG PS 2 mCRPC patients treated with abiraterone have inferior outcomes compared with ECOG 0- 1 patients, especially in regard to OS. These data indicate that early initiation of abiraterone prior to a decline in PS may be warranted. Patient summary: We found that advanced prostate cancer patients who have worse performance status ( PS) derive less benefit from abiraterone, indicating that earlier treatment before PS declines could improve outcomes. Crown Copyright # 2014 Published by Elsevier B. V. on behalf of European Association of Urology. All rights reserved.