265 Background: Few objective criteria are considered for risk stratification for treatment decision making in men with new mHSPC. Time between DT for localized disease, and start of ADT for new mHSPC may predict response to ADT, and prognosticate outcomes in this setting. Methods: In this multicenter study, men with newly diagnosed mHSPC with prior history of definite therapy for localized prostate cancer were included. Kaplan-Meier and Cox proportional hazard methods assessed time to castration resistance (CRPC) and overall survival (OS) from initiation of ADT, and correlated with the time elapsed from DT to initiation of ADT for new mHSPC. Results: A total of 112 men with new mHSPC initiating ADT, with prior definitive therapy were eligible (all median: age 68 yrs, Gleason score 7, PSA 14 ng/ml, ECOG 0, median time from DT to start of ADT for new mHSPC 54 months). In the univariate analysis, time from DT to start of ADT of < 60 months vs ≥ 60 months significantly correlated with duration of response to ADT and outcomes (Table). After adjustment for Gleason score and log PSA, time from DT to start of ADT for new mHSPC (<60 vs ≥60 months) remained an independent and a significant predictor of time to CRPC (HR 1.92 95% CI 1.02-3.90, p=0.044), and showed trends towards predicting OS (HR 1.77 95% CI 0.60-6.19, p=0.33). Conclusions: Time from DT for localized prostate cancer to initiation of ADT for new mHSPC independently predicts response to ADT, and may aid in risk stratification for treatment decision making in men with new mHSPC. These hypothesis-generating data require validation in a larger cohort. [Table: see text]