Unmet needs in non-metastatic castration-resistant prostate cancer from the Japanese patient perspective: a discrete choice experiment

OBJECTIVES: With novel antiandrogen treatments of varying clinical benefits and risks becoming available, this study investigates how patients with castration-resistant prostate cancer (CRPC) value differences in treatment characteristics. DESIGN: Cross-sectional observational study. SETTING: A discrete choice experiment was conducted. Patients chose between two hypothetical non-metastatic CRPC (nmCRPC) treatments defined by six attributes: risk of fatigue, falls or fracture, cognitive impairment, hypertension, rashes as side effects to treatment and extension of time until cancer-related pain occurs. PARTICIPANTS: A total of 137 adult male patients with CRPC with no prior experience with chemotherapy and with Eastern Cooperative Oncology Group status 0–1 were recruited. Patients were excluded if they participated in an investigational programme outside of routine clinical practice, had a clinically relevant medical or psychiatric condition, or diagnosis of visceral/other metastases not related to the prostate, or were otherwise deemed ineligible by the referring physician. PRIMARY OUTCOME MEASURES: Relative preference weights and relative importance of the attributes was estimated by hierarchical Bayesian logistic regression. RESULTS: Among the treatment attributes, ‘risk of cognitive impairment as a side effect of treatment’ was the most important attribute (relative importance (RI) (95% CI): 27.47% (24.80% to 30.14%)), followed by ‘extension of time until cancer-related pain occurs’ (RI (95% CI): 17.87% (15.49% to 20.25%)) and the ‘risk of falls or fracture’ (RI (95% CI): 15.99% (14.73% to 17.25%)). The ‘risk of hypertension as a side effect of treatment’ (RI (95% CI): 13.77% (12.73% to 14.81%)) had similar RI as ‘risk of rashes as a side effect of treatment’ (RI (95% CI): 13.17% (12.15% to 14.19%)), followed by the ‘risk of fatigue as a side effect of treatment’ (RI (95% CI): 11.74% (10.75% to 12.73%)). CONCLUSIONS: Patients consider the risk of cognitive impairment as a side effect of treatment as the most important attribute in nmCRPC, followed by the extension of time until cancer-related pain occurs, and the risk of falls and fracture. These features should be considered in treatment decision making for nmCRPC in Japan.