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deaths occurred, and median post-operative length of stay was 15 days. For the whole cohort median OS was 15.9 mo, with 13.5 mo for unresected pts, and not yet reached for resected pts (p=0.099). Conclusion This is a safe and feasible treatment regimen, response rates were as expected. R0 resection rate and early survival rates are encouraging. Development of a dose- escalated VMAT technique or margin-intensive SABR may further optimize the radiotherapy component of NAT. EP-1429 Stereotactic body radiation therapy as neoadjuvant/radical treatment for pancreatic adenocarcinoma X. Chen Zhao 1 , E. Sanchez Saugar 1 , M. Lopez Gonzalez 1 , O. Hernando Requejo 1 , A. Montero Luis 1 , J. Garcia Ruiz- Zorrilla 2 , M. De la Casa de Julian 2 , M. Garcia-Aranda Pez 1 , R. Ciervide Jurio 1 , J. Valero Albarran 1 , J. Palma Delgado 1 , R. Alonso Gutierrez 1 , J. Perez Moreno 2 , L. Alonso Iracheta 2 , D. Zucca Aparicio 2 , P. Garcia de Acilu 2 , J. Marti Asenjo 2 , P. Fernandez Leton 2 , C. Rubio Rodriguez 1 1 University Hospitals HM Sanchinarro - Puerta del Sur, Radiation Oncology, Madrid, Spain 2 University Hospitals HM Sanchinarro - Puerta del Sur, Medical Physics, Madrid, Spain Purpose or Objective Pancreatic adenocarcinoma (PA) remains one of the most lethal malignancies. Surgery is the only curative treatment. Chemotherapy (CH), radiotherapy or both are now been studied as neoadjuvant approaches. We are going to review feasibility and single centre experience with stereotactic body radiation therapy (SBRT) and a gating technique as a neoadjuvant or radical treatment in PA. Material and Methods Since February 2014, 23 patients (p) with a median age of 67.6 years (range 43-86) with histologically proven adenocarcinoma of the pancreas were enrolled on this protocol. Five p (21.3 %) were treated with a radical intent and 18 p (78.7 %) as a part of a neoadjuvant treatment. For all patients treated with neoadjuvant intent, CH had given before SBRT. Neoadjuvant CH schedule: 14 p received gemcitabine nab-paclitaxel, 3 p FOLFIRINOX and 1 patient with unknown CH schedule. Prior to radiation, at least 2 gold fiducials markers were located into the tumour guided by gastro-endoscopic ultrasound. All the SBRT treatments included intravenous and oral contrast CT or PET-CT for GTV delineation. Intensity-modulated radiation therapy (IMRT) and daily image-guided radiation therapy (IGRT) with intrafraction control of tumour motion with a Novalis Exactrac Adaptive Gating System were performed in all patients. Total dose: 50 Gy in 5 fractions were prescribed in 20 p (87%), 1 p was treated with 35 Gy in 5 fractions, 1 p was treated with 40Gy in 10 fractions and 1 p was treated with 50Gy in 10 fractions. Results With a median follow-up (FU) of 8.8 months (range 1 - 36 months), 7 p (30.4%) are alive without tumour, 4 p (17.4%) are alive with distance metastases and 12 p (52.2%) have died; median overall survival (OS) was 13.2 months (range 4.5 – 42.1 months) and the actuarial 12 and 24 months OS was 64.3% and 22% respectively. Twenty p (86.9%) remain locally controlled and median time to local progression was 12.7 (range 6.6 – 42 months). For any kind of progression disease, the actuarial progression-free survival at 12 and 24 months were 62.5% and 35.7% respectively. Fourteen patients (78%) underwent surgery. Tumour-free margins were achieved in all cases. Pancreatic SBRT was well tolerated in our cohort of patients. No grade 3 or higher toxicity was observed. Two p (8.7%) developed grade 2 epigastric pain and/or grade 2 asthenia.

Conclusion In our experience, SBRT for pancreatic tumour is a feasible and well-tolerated treatment. As neoadjuvant treatment, increase tumour- free margins surgeries in borderline and locally advanced stages. Most patients are free from local progression. The benefit of survival will be evaluated with longer FU. EP-1430 Biliary cancer definitive radiotherapy: an atlas for ctv definition with elective nodal irradiation S. Bisello 1 , L. Calculli 2 , M. Renzulli 2 , G. Sallustio 3 , G. Macchia 4 , F. Deodato 4 , G.C. Mattiucci 5 , S. Cilla 6 , S. Mignogna 7 , V. Picardi 4 , A. Guido 1 , L. Giaccherini 1,8 , A. Arcelli 1,9 , G. Siepe 1 , M. Buwenge 1 , S. Cammelli 1 , V. Valentini 5 , A.G. Morganti 1 1 Radiation Oncology Center, Department of Experimental- Diagnostic and Specialty Medicine - DIMES- University of Bologna, Bologna, Italy 2 Radiology Unit, Department of Diagnostic and Preventive Medicine- S. Orsola-Malpighi Hospital, Bologna, Italy 3 Radiology Unit, Fondazione di Ricerca e Cura “Giovanni Paolo II”, Campobasso, Italy 4 Radiotherapy Unit, Fondazione di Ricerca e Cura "Giovanni Paolo II", Campobasso, Italy 5 Department of Radiation Oncology, Sacred Heart Catholic University of Rome, Rome, Italy 6 Medical Physics Unit, Fondazione di Ricerca e Cura “Giovanni Paolo II”, Campobasso, Italy 7 Medical Oncology Unit, Fondazione di Ricerca e Cura “Giovanni Paolo II”, Campobasso, Italy 8 Radiation Oncology Unit, Department of Oncology and Advanced Technology, Arcispedale S. Maria Nuova-IRCCS of Reggio Emilia, Italy 9 Radiotherapy Department, Ospedale Bellaria, Bologna, Italy Purpose or Objective Radiotherapy (RT) is a treatment option for advanced biliary tumors, generally combined with sequential and/or concurrent chemotherapy. The use of modern RT techniques requires accurate definition of the Clinical Target Volume (CTV). We recently proposed guidelines to define the nodal CTV in these neoplasms (Marinelli I, et al, 2017). Aim of this study was to propose a CT atlas for CTV definition of biliary tumors candidates to exclusive RT