A real-world retrospective analysis of the management of metastatic castrate-resistant prostate cancer in Ontario, Canada from 2010 – 2018

We sought to quantify mCRPC patient treatment patterns and survival across multiple lines of therapy after prior androgen-receptor-axis-targeted therapy (ARAT) failure. Individuals diagnosed with prostate cancer between 2010 and 2018 were identified in the Ontario Cancer Registry (OCR). An algorithm was created to identify patients with mCRPC that was aligned to Prostate Cancer Clinical Trials Working Group 3 criteria (PCWG3) and validated with Canadian clinical experts. In the mCRPC setting, treatment patterns were assessed by line of therapy, and survival was calculated from treatment initiation until death or lost to follow-up. 64,484 men were diagnosed withprostate cancer in Ontario between 2010 and 2018with 5,588 men assessed to have mCRPC and 2,970 (53%) of those received first-line systemic treatment. Across the first-, second- and third-line of therapy, ARATs (abiraterone and enzalutamide) were the most used therapies. Survival for mCRPC patients treated with ARATs in first-, second- and third-line were 13.0 (95% CI, 11.6 – 14.5), 11.5 (95% CI, 10.1 – 13.4) and 8.9 (95% CI, 7.4 – 10.2) months, respectively. Survival for mCRPC patients treated with taxanes in first, second- and third-line were 16.7 (95% CI, 14.8 – 18.0), 11.3 (95% CI, 10.1 – 12.5) and 7.8 (95% CI, 6.5 – 10.6) months, respectively. No statistical difference in overall survival was found between taxanes and ARATs. In this analysis of a large retrospective cohort of Canadian men with mCRPC, we found that survival in patients treated with ARATs and taxanes was fairly similar across all lines of therapy. Importantly, this trend was maintained in ARAT-exposed patients, where sequential ARAT and taxanes offered similar survival. These data may help inform optimal sequencing of therapies in mCRPC.