Introduction: The Italian Association of Medical Physics (AIFM) instituted in 2012 a working group dedicated to stereotactic body radiation therapy (SBRT). The present study was developed in the framework of this project.

Gleason Score (GS) < 7; the mean of iPSA was 18 ng/mL; the rate of clinical positive nodes was 1%.The ADT was prescribed to 69% of patients in neoadjuvant setting, 65% in concomitant setting and 34% in adjuvant setting.The mean follow-up was 81 months. Results:The prognostic factors resulted statistically significant for all groups of patients at both, univariate and multivariate analysis, were the GS and the iPSA.In intermediate and high/very-high risk patients at multivariate analysis the prognostic factors for CSOS were: GS (p= 0.001), positive lymph nodes on CT scan (p = 0.05) and rectal preparation during the treatment (p= 0.005); for the BDFS were: GS (p= 0.008), patient risk classification (p= 0.037), positive lymph nodes on CT scan (p= 0.004), iPSA (p= 0.001) and rectal/bladder preparation during the radiation treatment (p=0.001); for the CDFS were: number of positive core on biopsy (p= 0.003), GS (p= 0.0003), positive lymph nodes on CT scan (p= 0.015), iPSA (p= 0.0056) and RT dose (p = 0.001).In high/very-high risk patient group at multivariate analysis the prognostic factors for CSOS were: biopsic Gleason Score, clinical/radiological stage, RT dose; for BDFS were: biopsic Gleason Score, adjuvant ADT, clinical/radiological stage, iPSA and RT dose>77.7 Gy; for CDFS were: biopsic Gleason Score, clinical/radiological stage, iPSA and RT dose>77.7 Gy. Conclusion:Our results confirm several prognostic factors already described by literature, adding a new prognostic factor represented by the rectal/bladder preparation, generally known for its effect on toxicity but not yet on outcome.We believe that in the future a new nomogram should include also some therapeutic variables (as RT dose, RT technique and ADT), to help clinicians in decision-making.