To assess treatment patterns and outcomes of patients with metastatic castration-resistant prostate cancer (mCRPC) receiving first-line chemotherapy or anti-androgen therapy.
Patients initiating first-line anti-androgen therapy (abiraterone, enzalutamide) or chemotherapy (taxane) from Oct/2012-Sept/2014 were retrospectively identified in the US Veterans Health Administration (VHA) database. The impact of anti-androgen therapy versus chemotherapy on overall survival (OS) and time to discontinuation was assessed using Cox proportional hazard models, adjusting for prior androgen deprivation therapy (ADT) duration and available prognostic factors.
Overall, 1,445 patients were evaluable; 1,108 received anti-androgen therapy and 337 received chemotherapy (docetaxel). On multivariable analysis and propensity score analysis, OS for anti-androgen therapy versus chemotherapy was not significantly different (HR: 1.041, 95% CI: 0.853-1.270; P = 0.6943 and HR: 1.047, 95% CI: 0.861-1.273; P = 0.6444, respectively). Time to discontinuation was shorter for chemotherapy versus anti-androgen therapy (HR: 2.339, 95% CI: 1.969-2.779; P < 0.0001). Prior ADT duration above median was associated with longer OS (HR: 0.566, 95% CI: 0.464-0.690; P < 0.0001) and time to discontinuation (HR: 0.831, 95% CI: 0.699-0.988; P = 0.0363) in the anti-androgen therapy cohort and not the chemotherapy cohort, while prior ADT duration below median was associated with higher PSA response rate in the chemotherapy versus anti-androgen therapy cohort (61.5% vs 51.1%; P = 0.0241). Treatment-free interval following discontinuation was longer after first-line chemotherapy versus anti-androgen therapy (mean: 53 vs 39 days; P = 0.0303).
OS was similar for first-line chemotherapy versus anti-androgen therapy after adjusting for key prognostic factors in this large mCRPC dataset, despite shorter time to discontinuation with chemotherapy and longer treatment-free interval after first-line chemotherapy. These hypothesis-generating data also suggest that duration of prior ADT may assist in the selection of patients for chemotherapy versus anti-androgen therapy. This article is protected by copyright. All rights reserved.
BJU international. 2018 Feb 01 [Epub ahead of print]
Guru Sonpavde, Ahong Huang, Li Wang, Onur Baser, Raymond Miao
Dana Farber Cancer Institute, Boston, MA, USA., STATinMED Research, Ann Arbor, MI, USA., Sanofi, Bridgewater, NJ, USA.