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.