Patterns of care for patients with non-metastatic castration-resistant prostate cancer: Population-based study in Ontario, Canada.

53 Background: To describe patterns of practice of PSA testing and imaging for Ontario men receiving continuous androgen deprivation therapy (ADT) for the treatment of non-metastatic castration-resistant prostate cancer (nmCRPC). Methods: This was a retrospective, longitudinal, population-based study of administrative health data from 2008 to 2019. Men > 65 years old receiving continuous ADT with documented CRPC were included. An administrative proxy definition was applied to capture patients with nmCRPC patients and excluded those with metastatic disease. Patients were indexed upon progression to CRPC and were followed until death or end of study period to assess frequency of monitoring with PSA tests and conventional imaging. A 2-year look-back window was used to assess patterns of care leading up to CRPC, as well as baseline covariates. Results: At a median follow-up of 40 months, 944 patients with CRPC were identified. Their median time from initiation of ADT to CRPC was 26 months, 61% of patients had their PSA measured twice or fewer in the year prior to index and 71% patients did not receive any imaging in the year following progression to CRPC. Almost all patients (98%, n = 921/944) in the study progressed to high-risk CRPC (HR-CRPC) during the study period, of which more than half received fewer than 3 PSA tests in the year prior to progression to HR-CRPC, and 31% received no imaging in the subsequent year. Conclusions: PSA testing and imaging studies are under-utilized in a real-world setting for the management of nmCRPC, including those at high-risk of developing metastatic disease. Infrequent monitoring impedes proper risk stratification, disease staging, detection of treatment failure and/or metastases, likely delaying necessary treatment intensification with life-prolonging therapies. Adherence to guideline recommendations and the importance of timely staging should be reinforced to optimize patients’ outcome.