Population-Based Analysis of Treatment Toxicity among Men with Castration-Resistant Prostate Cancer: a Phase IV Study

To assess the toxicity and effectiveness of contemporary metastatic castrate-resistant prostate cancer (mCRPC) treatments at a population-level, among all patients in Ontario particularly treated with newer agents including abiraterone, enzalutamide, docetaxel and cabazitaxel.

We performed a population-based, retrospective cohort study of 2439 men aged ≥65 years treated for mCRPC with abiraterone, enzalutamide, docetaxel, or cabazitaxel from 2003-2015 in Ontario, Canada. Our primary outcome was treatment related toxicity, defined as hospitalizations and ER visits during mCRPC treatment. Based on toxicity profiles identified during phase III trials, we further identified specific treatment-related toxicity. We calculated hazard ratios (HRs) using multivariable Cox proportional hazards models with time-varying exposures.

Abiraterone and enzalutamide exposure were not associated with any-cause (p=0.19 and 0.52, respectively) or treatment-related (p=0.45 and 0.64, respectively) toxicities. In contrast, docetaxel exposure was associated with an increased risk of any-cause (HR 1.29, 95%CI 1.15-1.44) and treatment-related (HR 1.52, 95%CI 1.33-1.74) toxicity. Cabazitaxel exposure was associated with a significant risk of treatment-related (HR 5.94, 95%CI 1.87-18.92) but not any-cause (HR 2.37, 95%CI 0.59-9.63) toxicity.

Among patients with mCRPC, we failed to show any increased risk of hospitalizations and ER visits for treatment related complications for abiraterone or enzalutamide. In contrast, treatment with intravenous chemotherapeutic agents was associated with an increased risk of hospitalizations and ER visits to manage these complications.

Urology. 2017 Nov 27 [Epub ahead of print]

Christopher J D Wallis, Raj Satkunasivam, Refik Saskin, Symron Bansal, Girish S Kulkarni, Urban Emmenegger, Robert K Nam

Division of Urology, Sunnybrook Health Sciences Centre, University of Toronto; Institute for Health Policy, Management & Evaluation, University of Toronto., Division of Urology, Sunnybrook Health Sciences Centre, University of Toronto., Institute of Clinical Evaluative Sciences, Sunnybrook Research Institute, University of Toronto., Division of Urology, University Health Network, University of Toronto., Division of Medical Oncology, Sunnybrook Health Sciences Centre, University of Toronto., Division of Urology, Sunnybrook Health Sciences Centre, University of Toronto; Institute for Health Policy, Management & Evaluation, University of Toronto. Electronic address: .

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