INTRODUCTION:We aimed to characterize demographic distribution, patient outcomes, and prognostic features of testicular sex cord stromal tumours (SCST) using a large statewide database. METHODS:Adult male patients diagnosed with SCST between 1988 and 2010 were identified within the California Cancer Registry (CCR). Baseline demographic variables and disease characteristics were reported. Primary outcome measures were cancer-specific survival (CSS) and overall survival (OS). Bivariate and multivariate Cox proportional hazards models were employed to identify predictors of survival. RESULTS:A total of 67 patients with SCST were identified, of which 45 (67%) had Leydig cell and 19 (28%) had Sertoli cell tumours. Median age was 40 years and the majority of patients (84%) presented with localized disease. Following orchiectomy, nine patients (15%) underwent retroperitoneal lymph node dissection (RPLND), whereas 54 patients (80%) had no further treatment. With a median followup of 75 months, two-year OS and CSS was 91% and 95%, respectively, for those presenting with stage I disease. For those presenting with stage II disease, two-year OS and CSS was 30%. Predictors of worse OS included age >60 (hazard ratio [HR] 5.64; p<0.01) and metastatic disease (HR 8.56; p<0.01). Presentation with metastatic disease was the only variable associated with worse CSS (HR 13.36; p<0.01). Histology was not found to be a significant predictor of either CSS or OS. CONCLUSIONS:We present the largest reported series to date for this rare tumour and provide contemporary epidemiological and treatment data. The primary driver of prognosis in patients with SCST is disease stage, emphasizing the importance of early detection and intervention.