Both abiraterone and enzalutamide have shown to improve overall survival (OS), progression-free survival (PFS) and PSA response in patients with metastatic castration-resistant prostate cancer (MCRPC) regardless of previous treatment with chemotherapy (COU-AA301, COU-AA302, AFFIRM and PREVAIL). The data regarding the impact of these treatments in regional health services is scarce. This study assessed the survival outcomes in MCRPC patients in a regional health service in Victoria with the use of abiraterone and enzalutamide.
This retrospective clinical audit included 75 patients with the diagnosis of MCRPC treated with either abiraterone or enzalutamide between the period of January 1 2014 to December 31 2019 at Goulburn Valley Health. Patients were divided into two groups based on whether they received abiraterone or enzalutamide, and stratified according to ECOG performance, Gleason score, burden of disease, presence of visceral metastases and use of previous chemotherapy. The primary end point was PSA response. The secondary outcomes were PSA PFS, radiographic PFS, and OS.
37 patients received enzalutamide, and the other 38 received abiraterone. Only 20% of patients in either group had visceral metastases. 32% of patients receiving enzalutamide had a high burden of disease, compared to 53% receiving abiraterone. 38% of patients in the enzalutamide group and 53% in the abiraterone group had received prior chemotherapy. PSA response rates were higher in the enzalutamide group than abiraterone group (70.3% vs 37.8%). Both PSA and radiographic PFS were longer in the enzalutamide group than abiraterone group; 7 months vs 5 months for both end points. OS was also found to be longer in patients receiving Enzalutamide; 30 months compared to 13 months in patients receiving Abiraterone.
Both abiraterone and enzalutamide have shown to result in significant PSA response rates, as well as PFS and OS benefit in MCRPC patients in the real-world setting, as reflected in previous clinical trials. The difference in responses and survival benefit between the groups are probably impacted by the unbalanced burden of disease and proportion of prior chemotherapy use.
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Has not received any funding.
All authors have declared no conflicts of interest.