Abstract
The treatment paradigm for non-metastatic castration-resistant prostate cancer (nmCRPC) has changed in recent years. An observational multicenter study was conducted to evaluate the effectiveness of androgen receptor signaling inhibitors (ARSIs) as a first-line treatment for patients with nmCRPC. The present study included native Japanese patients from four hospitals who received ARSIs as a first-line treatment for nmCRPC. The primary endpoint of the study was to evaluate the efficacy and safety of ARSI in patients with nmCRPC. The secondary endpoint was to develop a novel system to stratify the prognoses of these patients. In total, 160 patients were included in the present study. Within a median follow-up period of 23 months, the median overall survival (OS) was not reached, whereas the median progression-free survival was 26 months. Multivariate Cox regression analyses showed that the time to CRPC, prostate-specific antigen (PSA) level at the initiation of nmCRPC treatment and Geriatric Nutritional Risk Index (GNRI) were independent predictors of OS. The patients for whom information about all three independent OS predictors was available were subsequently divided into three groups as follows: Group 1, 57 patients with negative or one positive independent OS predictor; group 2, 38 patients with two positive independent OS predictors; and group 3, 10 patients with three independent OS predictors. The OS differed significantly among the three groups (P<0.0001). In conclusion, ARSIs as a first-line treatment may be associated with favorable outcomes in Japanese patients with nmCRPC. Time to CRPC, PSA level at the initiation of nmCRPC treatment and GNRI are potential predictors of OS in Japanese patients with nmCRPC who received ARSIs as a first-line treatment.