ESTRO 37 Abstract book

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ESTRO 37

Conclusion We generated predicted tumor-regression CT images from baseline CT using deep learning algorithm. These images could be utilized to determine the timing of the adaptive planning or to calculate dose distribution to the regressed tumor in advance. More large data and well designed train set configuration is essential to elevate the accuracy of the predicted tumor-regression CT images. EP-1371 Stereotactic body radiotherapy for stage I lung cancer. P.M. Samper Ots 1 , C. Vallejo Ocaña 2 , P. Alcantara 3 , M.D.M. Puertas 4 , M. Rico Osés 5 , M.L. Couselo 6 , A. Sotoca Ruiz 7 , J. Luna Tirado 8 , J.L. Monroy 9 , P. Almendros Blanco 10 1 Hospital Rey Juan Carlos, Servicio de Oncologia Radioterapia, Mostoles - Madrid, Spain 2 Hospital Ramon y Cajal, Servicio de Oncología Radioterapia, Madrid, Spain 3 Hospital Clinico, Servicio de Oncología Radioterapica, Madrid, Spain 4 Hospital Miguel Servet, Servicio de Oncología Radioterapica, Zaragoza, Spain 5 Complejo Hospitalario de Navarra, Servicio de Oncologia Radioterápica, Navarra, Spain 6 Hospital Central de la Defensa, Servicio de Oncología Radioterápica, Madrid, Spain 7 Hospital Ruber Internacional, Servicio de Oncología Radioterápica, Madrid, Spain 8 Fundación Jimenez Diaz, Servicio de Oncología Radioterápica, Madrid, Spain 9 Hospital de Alzira, Servicio de Oncología Radioterápica, Valencia, Spain 10 Hospital General de Valencia, Servicio de Oncología Radioterápica, Valencia, Spain Purpose or Objective The purpose of this study was to evaluate treatment patterns and outcomes of stereotactic body radiotherapy (SBRT) for early primary non-small cell lung cancer (NSCLC). Material and Methods Multicentric retrospective study of 139 patients with early non-small cell lung cancer, treated in ten Spanish centers between 2010 and 2016, 124 (89%) were males and 15 females, with a mean age of 73.7 years, received treatment with SBRT for 148 lung lesions. 93.9% of the patients were inoperable. A total of 64 cases (43.2%) had no pathological diagnosis, 41 (27.7%) were adenocarcinoma, 38 (25.7%) epidermoid, 1 (0.7%) indiferenciated large cells and 4 (2.7%) non-small cell. 143 lesions (96.6%) had increased metabolism in the PET/CT with an average SUV of 8.5 ± 5.7. The location of the lesions was: central 44 (29.7%), medium 34 (23%) and peripheral 70 (47.3%). The mean lesion size was 22 ± 10 mm. 74 (50%) were T1a, 42 (28,4%) T1b, 26 (17,6%) T2a and 5 (3,4%) T2b. The LSI and LSD were the most frequent localization with 49 (33%) and 44 (29.7%) lesions respectively. We performed CT simulation of normal, inspiration and expiration in 123 patients (83%) and 4D CT in 25 (16.9%). A stereotaxic immobilization system was used in 137 cases (92.6%). Control of respiration system were with dampening in 137 (92.6%), tracking 7 (4.7%) and gating 4 (2.7%). The prescription dose ranges from 30 - 70 Gy, with 60 Gy being the most frequent in 120 lesions (81%). The schemes used were: 60 Gy (5 fx of 12 Gy) in 43,2%; 60 Gy (8 fx of 7.5 Gy) in 37,2%. Treatment was given on alternate days in most cases 118 (80%). BED was <100 Gy in 3 (2.1%), 100 Gy in 17 (12%) and >100 Gy in 123 (83%). Type of RT: RC3D 70 (47.3%), VMAT 52 (35.1%), IMRT 17 (11.5%) and CiberKnife 9 (6.1%). Results With a follow-up of 2 years, 68 lesions (47.6%) had complete response in CT, 63 (92.6%) of which had

received a BED> 100 Gy (p = 0.003). 74 lesions (51.7%) had complete response in the PET/CT, 61 (82.4%) had received BED> 100 Gy (p = 0.008). Local failure was seen in 11 patients (7.4%), regional failure in 14 (9.5%) and metastasis in 25 (16.9%), being the main site of relapse. The time to local failure, regional failure and metastases were 1,3±0,6 years, 1,2±0,6 years and 1,2±1,2 years, respectively. 84 patients (56.8%) are alive without disease and 19 (12.8%) are alive with disease, 11 patients (7.4%) have died from tumor and the rest died from other causes. Mean overall survival was 4.33 ± 0.2 years (95% CI 3.93-4.72). 3.9 ± 0.21 years (95% CI 3,479-4,329).

Conclusion SBRT is a safe and effective treatment for patients with early stage of lung cancer inoperable or who refuse surgery. To improve the control it is necessary to give a dose with BED > 100 Gy. EP-1372 DART-bid with VMAT for locally advanced NSCLC R. Pinter 1 , K. Wurstbauer 1 , M. Kazil 1 , M. Meinschad 2 , P. Cerkl 3 , T. Künzler 2 , P. Clemens 1 , A. De Vries 1 1 Landeskrankenhaus Feldkirch, Radiation Oncology, Feldkirch, Austria 2 Landeskrankenhaus Feldkirch, Medical Physics, Feldkirch, Austria 3 Landeskrankenhaus Hohenems, Pneumology, Hohenems, Austria Purpose or Objective Results of DART-bid treatment (dose-Differentiated Accelerated Radiation Therapy, 1.8 Gy twice a day) with “Target-Splitting” are sufficiently published. Basics are: