Comparative Effectiveness of First-Line Treatments for Castration-Resistant Prostate Cancer: A Large-Scale Retrospective Study in Japan.

[OBJECTIVES] Prostate cancer is the fifth leading cause of cancer-related death in men worldwide, with particularly high mortality rates in countries with large Black populations, and the United States. Despite the prevalence of prostate cancer screening, advanced cases are still diagnosed, with 10%-20% of these progressing to castration-resistant prostate cancer (CRPC) within 5 years. The survival of patients with CRPC is limited, which emphasizes the need for effective treatment strategies.

[METHODS] The study utilized a database of Japanese DPC hospitals, comprising approximately 25.6% coverage. From April 2008 to December 2022, 410,000 patients with prostate cancer were identified, of whom 25,934 were diagnosed with CRPC. A subset of 20,177 patients who received treatment for CRPC was selected for further analyses. The study focused on three treatments: abiraterone acetate (ABI), enzalutamide (ENZ), and docetaxel (DOC), excluding other treatments due to relatively low patient numbers. The analysis included age, date of the diagnosis of CRPC, presence of bone metastasis, agent type, and prognosis.

[RESULTS] The study enrolled 18,924 patients with CRPC who were treated with ENZ, ABI, or DOC as the first-line treatment. In the overall population, ENZ was associated with prolonged OS in comparison to ABI (HR: 0.903, p < 0.003). In patients with bone metastases, no significant difference was found in treatment efficacy between ABI and ENZ. Sequential therapy starting with ABI followed by ENZ did not result in a significant difference in time to treatment failure but was associated with a slight improvement in overall survival.

[CONCLUSIONS] This retrospective study, based on a large-scale Japanese database, indicates that ENZ may be the most effective first-line treatment for Japanese patients with CRPC, especially given its favorable outcomes relative to other treatments. Despite the limitations in the data set, the findings support the use of ABI-ENZ sequential therapy, which may provide additional clinical benefits in terms of overall survival.

[TRIAL REGISTRATION] N/A.