Risk Stratification for the Prediction of Overall Survival Could Assists Treatment Decision Making at the Diagnosis of Castration‐Resistant Prostate Cancer – a Multicenter Collaborative Study in Japan

OBJECTIVES This study aimed to assess whether the new risk stratification according to predictors for overall survival (OS) at the diagnosis of metastatic castration-resistant prostate cancer (mCRPC) could determine the treatment outcomes and assist the treatment decision making. SUBJECTS AND METHODS Two independent clinical cohorts of patients treated with androgen signaling inhibitors (ASIs: abiraterone and enzalutamide) or docetaxel as a first-line treatment for mCRPC were utilized as the derivation cohort (196 mCRPC patients) and the external validation cohort (211 mCRPC patients). RESULTS Three independent predictors for OS, including duration of initial ADT 350 U/dL and hemoglobin <11g/dL at the diagnosis of mCRPC were defined as risk factors. Patients with no, one, and multiple risk factors were assigned to the favorable, intermediate, and poor-risk groups, respectively. A median OS in each risk group was well-separated in the derivation cohort (p<0.0001) as well as the validation cohort (p<0.0001). In a total of 407 mCRPC patients, 84 patients were assigned to the poor risk with the median OS of 12 months, in which trend towards longer OS favoring docetaxel compared to ASIs as the first-line treatment (a median of 17 and 12 months, respectively) was observed. CONCLUSION The new risk group stratification could predict patient survival at the diagnosis of CRPC. Given the convenience for the definition, physicians may be encouraged to consider the risk group for the daily practice.