Clinical outcomes and prognostic factors in patients with newly diagnosed metastatic prostate cancer initially treated with androgen deprivation therapy: a retrospective multicenter study in Japan

Purpose: Clinical outcomes of patients with newly diagnosed metastatic hormone-naïve prostate cancer (mHNPC) and initially treated with androgen deprivation therapy (ADT) were evaluated. Methods: The medical records of 605 consecutive mHNPC patients with initial ADT or combined androgen blockade (CAB) at nine study centers between 2008 and 2016 were retrospectively reviewed. Castration-resistant prostate cancer (CRPC)-free and overall survival (OS) were estimated by the Kaplan–Meier method. The association of pretreatment risk factors with CRPC-free survival and OS was evaluated by Cox proportional hazard models and differences in survival were classified by the number of risk factors. Results: Median follow-up was 2.95 years, median CRPC-free survival was 21.9 months and median OS was 5.37 years. Multivariable analysis found that four risk factors, a Gleason score ≥ 9, lymph node metastasis, an extent of disease score ≥ 2, and serum LDH of > 220 IU were independently associated with both CRPC-free survival and OS. Median CRPC-free survival of low-risk patients with no or one factor was 86.5 months, 17.9 months in intermediate-risk patients with two or three factors, and 11.0 months in high-risk patients with four factors. Median OS was 4.72 years in intermediate- and 2.44 years in high-risk patients. It was not reached in low-risk patients. Conclusion: In this series, CRPC-free and OS of a subset of mHNPC patients in Japan who were treated with ADT or CAB had better CRPC-free and overall survivals in Japan. Risk-adapted treatment based on the presence of novel prognostic factors may be beneficial for selected mHNPC patients.