Purpose/Objective: This study explores the results, in term of Local Control (LC) and Disease Free Survival (DFS), of SBRT used to eradicate nodal recurrence of prostate cancer assessed by Choline-PET scan. Materials and Methods: 103 patients with biochemical relapse were examined by Choline-PET scan to select those with recurrences limited to nodal sites. A total number of 40 patients were selected and treated with ablative SBRT. Among these 7 patients were previously treated for primary tumor

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... with surgery, 11 with radiotherapy and 22 with both. Median age was 65 years (range 46-85). SBRT was delivered by 6 MV Linac (Elekta Synergy), using dynamic micromultileaf collimator and intensity-modulated arc therapy optimization. During the follow-up the patients were submitted to Choline-PET scan, Computed Tomography and PSA dosage sixty days after treatment and then every 4 month. Results: Median follow-up was 57 months (range 3-127). At the time of analysis 25/40 (62.5%) patients were still alive, 13/40 (32.5%) were dead and 2/40 (5%) were lost in followup. Median PSA was 1.04 ng/ml (range 0.1-77.6) in patients with Choline-PET negative and 5.65 ng/ml (range 0.37-181.6) with Choline-PET positive scan (p<0.05). Among treated patients 15/40 were with no evidence disease (NED) at the last follow up while 25/40 relapsed out of treated field (4 pts in bone and 6 in lymph nodes other then treated). Disease Free Survival, Overall Survival and Local Control rates at 2 and 5 years were 50%, 92% and 90%, and 17%, 56.3% and 90%, respectively. Any severe acute or late GI and/or GU toxicity (≥G3) was not observed but only mild GI late toxicity in 15% of patients. Conclusions: Our results confirmed that SBRT for isolated nodal relapses from prostate cancer is effective ablative treatment with high LC probability rates and is well tolerated also. Based on results regarding the survival and disease progression SBRT could be considered as a possible alternative treatment able to preserve and/or postpone the systemic treatments or androgen deprivation therapy in patients with isolated relapse of disease. Choline-PET scan is useful diagnostic option in order to detect both disease progression to lymph-node sites and to evaluate the results of SBRT. Purpose/Objective: To analyse if Image guided Radiotherapy (IGRT), made on prostate cancer patients treated with Simultaneous Integrated Boost technique, could help to personalise treatment. PO-0744 Develope predictive models to foresee toxicity: validation of a software to help clinicians Purpose/Objective: Elaborate predictive model is the new challenge to personalize treatment on a single patient. Radiobiological models describe effects of radiation