ESTRO 2021 Abstract Book

S180

ESTRO 2021

Conclusion We have identified risk factors for the development of cardiac toxicity after different treatment modalities. However, all models should be improved, e.g. by incorporating detailed cardiac parameters (substructures’ volumes and doses). PH-0271 Mid-p strategy versus ITV strategy in locally advanced lung cancer. A randomized phase II study L. Claude 1 , V. Isnardi 2 , C. Schiffler 3 , S. Metzger 4 , I. Martel-Lafay 5 , S. Rit 6 , D. Sarrut 6 , T. Baudier 6 , M. Ayadi 5 1 centre Léon Bérard, Radiation Oncology Department, Lyon , France; 2 centre Léon Bérard, Nuclear Medicine Department , Lyon, France; 3 centre Léon Bérard , Innovation and clinical research department, Lyon, France; 4 Centre Léon Bérard, Innovation and clinical research department, Lyon, France; 5 Centre Léon Bérard, Radiation Oncology department, Lyon, France; 6 Centre Léon Bérard, CREATIS, UMR CNRS 5220, Inserm U1294 , Lyon, France Purpose or Objective The overall survival (OS) of patients (pts) with non-resectable locally advanced non-small cell lung carcinoma (LA-NSCLC) is poor, in part due to insufficient local control (LC) using conformal irradiation techniques (RT). The personalization of the RT margins may impact the LC and the outcome. Internal Target Volume strategy (ITV) versus "Mid-position" strategy (Mid-p), was compared in a prospective non-comparative randomized monocentric phase II trial in NSCLC patients treated by definitive radiotherapy. Planning Target volumes and mean lung dose were previously reported as significantly reduced using the Mid-p strategy (DOI: 10.1259/bjr.20190692). We report here the clinical results. Materials and Methods Eligible patients were randomized (2:1) to be treated with Mid-p or ITV strategies. Patients with proven LA- NSCLC, non-resected, non-metastatic treated by definitive RT could be included. The main objective was to