Understanding Treatment Strategies and Preferences in Nonmetastatic Castration-Resistant Prostate Cancer From the Japanese Physician Perspective

PURPOSE: Sixteen percent (16%) of patients with castration-resistant prostate cancer (CRPC) show no bone metastasis at diagnosis. However, 33% will become metastatic within 2 years. The goal of treatment in patients with nonmetastatic CRPC (nmCRPC), therefore, is to delay symptomatic metastases without undue toxicity. With novel antiandrogen treatments of different strengths and limitations available, physician preferences for nmCRPC treatment in Japan should be understood. METHODS: A discrete choice experiment was conducted. Physicians chose between two hypothetical treatments in nmCRPC defined by six attributes: risk of fatigue, falls or fracture, cognitive impairment, hypertension, rashes as side effects of treatment, and extension of time until cancer-related pain occurs. Relative preference weights and relative importance were estimated by hierarchical Bayesian logistic regression. Physicians were also asked to make treatment decisions based on four hypothetical patient profiles to understand the most important factors driving decision making. RESULTS: A total of 151 physicians completed the survey. Extension of time until cancer-related pain occurs was the most important attribute (relative importance, 32.3%; CI, 31.3% to 33.3%). Based on summed preference weights across all attributes, preferences for hypothetical treatment profiles I, II, and III were compared. A hypothetical treatment profile with better safety though shorter extension time was preferred (I: mean [standard deviation] = 1.7 [1.6 to 2.1]) over treatment profiles with lower safety but longer extension time (II: −2.7 [−2.8 to −2.6] and III: −0.2 [−0.3 to −0.1]). Treatment characteristics were more important factors for physicians' decision making than patient characteristics in prescribing treatment. CONCLUSION: Physicians preferred a treatment with better safety profile, and treatment characteristics were the most important factors for decision making. This might have implications in physicians' decision making for nmCRPC treatment in the future in Japan.