COMPARISON OF FIRST-LINE DOCETAXEL OR ABIRATERONE/ENZALUTAMIDE IN LOW AND HIGH-VOLUME DISEASE MET-ASTATIC CASTRATION RESISTANT PROSTATE CANCER

Introduction: Chemotherapy with docetaxel (Doc) or hormonotherapy (HT) with abiraterone/enzalutamide (Abi/EZ) are currently options of first-line therapy (1stL) in metastatic castration resistant prostate cancer (mCRPC). However, there are no prospective comparisons that define the best treatment choice in the different presentations of mCRPC. Objectives: The primary objective was to compare progressionfree survival (PFS) between HT and Doc in high-volume disease (visceral disease or ≥ 4 bone lesions with at least one extra-axial) – HD – and low-volume disease (LD) mCRPC. Secondary objectives were to evaluate PFS and overall survival (OS) in global population; OS and PFS in second line therapy (PFS2) in HD and LD; to define prognostic factors. Methods: Retrospective analysis of mCRPC patients (pts) treated with Doc or HT with Abi/EZ in 1stL were conducted in a single center in Brazil. Descriptive statistics were used to determine population characteristics. Kaplan-Meier, Log-Rank Test and Cox Regression were used for survival analysis. Results: From January, 2012 to September, 2017, 167 pts with mCRPC received 1stL. 65 (38.9%) were alive at cut-off date. Median follow-up was 41 months (m). Median age at diagnosis was 64 (44-84) years, Gleason score was 8, and initial PSA 19 (1.2-5000). 140 (83.8%) pts had high risk according Damico criteria. 97 (58.1%) had HD and 70 (13.8%) LD in 1stL. 114 (68.3%) underwent HT and 53 (31.7%) Doc. Median PFS and OS of global population were 9.0m (95%CI 7.30-10.70) and 32m (95%CI 28.3-35.7), respectively. PFS was superior for HT versus Doc (12m vs 5m; HR 2.76, 95%CI 1.91-3.98; p < 0.001) and OS did not differ between the groups (33m vs 28m; HR 1.16, 95%CI 0.77-1.75; p = 0.46). In LD group, 13 (18.6%) underwent Doc and 57 (81.4%) HT. Median PFS was 13m (95%CI 9.58-16.42). PFS for HT was 17.0m and for Doc 4.0m (HR 4.46, 95%CI 2.20-9.01; p < 0.001). In HD group, 40 (41.2%) underwent Doc and 57 (58.8%) HT. Median PFS was 7m (95%CI 5.49-8.51). PFS for HT was 8.0m and for Doc 5.0m (HR 1.89, 95%CI 1.22-2.92; p = 0.004). PFS2 and OS were similar for HT and Doc in the two groups. HT and PSA decrease ≥ 50% (PSAde) were associated with prolonged PFS in multivariate analysis either in LD or HD. HD was an independent risk for inferior OS in global population multivariate analysis. Conclusions: HT with Abi/EZ was associated with prolonged PFS either in HD or LD groups, as was PSAde. Pts with HD had inferior OS than pts with LD.