ESTRO 36 Abstract Book

S267 ESTRO 36 2017 _______________________________________________________________________________________________

Marseille, France 7 Department of Radiation Oncology -Centre Oscar Lambret- Lille- France, Department of Radiation Oncology, LILLE, France 8 Department of Radiation Oncology- Institut Curie- Paris- France, Department of Radiation Oncology, Paris, France 9 Department of Radiation Oncology- Institut de cancérologie de l’ouest- Nantes- France, Department of Radiation Oncology, Nantes, France 10 Department of Radiation Oncology - CHU Bordeaux- Bordeaux- France, Department of Radiation Oncology, Bordeaux, France 11 Department of Radiation Oncology- Centre Alexis Vautrin- Vandoeuvre- Nancy- France, Department of Radiation Oncology, Nancy, France 12 Department of Radiation Oncology- Centre Léon Bérard- Lyon- France, Department of Radiation Oncology, Lyon, France 13 Department of pediatric- Hematology-Oncology Unit- CHU Purpan- Toulouse- France, Department of pediatric, Toulouse, France 14 ToNIC- Toulouse NeuroImaging Center- Université de Toulouse- Inserm- UPS- Toulouse- France, Toulouse NeuroImaging Center, Toulouse, France 15 Department of Nuclear Medicine- CHU Purpan- Toulouse- France- ToNIC- Toulouse NeuroImaging Center- Université de Toulouse- Inserm- UPS- Toulouse- France, Department of Nuclear Medicine, Toulouse, France 16 Department of Radiation Oncology- Institut Claudius Regaud- Institut Universitaire du Cancer de Toulouse – Oncopole- Toulouse- France- ToNIC- Toulouse NeuroImaging Center- Université de Toulouse- Inserm- UPS- Toulouse- France, Department of Radiation, Purpose or Objective The aim of this study was to investigate the correlation between preoperative, postoperative imaging characteristics and survival after radiotherapy in pediatric A retrospective review of 121 patients who underwent primary resection of ependymoma followed by radiation therapy was undertaken utilizing quantitative volumetric analysis of pre- and postoperative MR images. Preoperative tumor volume (PRTV) on Post contrast (PC) T1 imaging , preoperative tumor volume ((PRTVF) on T2/FLAIR imaging , postoperative tumor volume on T2/FLAIR (POTVF) and Contrast Enhancement volume (CEPTV) ) on PC-T1 imaging were delineated by an experienced radiation oncologist and double-checked by a neuroradiologist, after coregistration of T2/FLAIR imaging to the PC-T1WI. A survival analysis was done including clinical data (Gender, tumor location, tumor grade, the extent of resection, radiation dose) and extracted imaging volumes. All survival times were calculated from the date of beginning of RT. Overall survival (OS) and disease free survival (DFS) were estimated by the Kaplan-Meier method and using the following first-event definitions: local and distant relapse or death for disease free survival (DFS) and death for overall survival (OS). Univariate analyzes were performed using Cox proportional hazards model for quantitative variables and the log-rank test for qualitative variables. The hazard ratio (HR) (respectively, the survival rate at 3 years) is presented for each quantitative covariate (qualitative respectively) with 95% confidence interval. PRTV variable was dichotomized with the median value (<= 43.8 cc, vs> 43.8 cc) and POTVF variable with (0 (no) vs> 0 (presence)). Results At the end of analysis, 80.2 % of patients were alive, 39.7% presented with one events (local relapse, distant relapse or death). The median overall survival was 38.5 months (9% IC [30.5; 47.7]). The Median age at diagnosis was 4 years (1.0-22.0), 58.7% were male, tumor location was ependymoma patients. Material and Methods

Conclusion Following de-intensified chemoradiotherapy, the rate of patient reported xerostomia was best correlated with V15- V55 of the combined contralateral glands at 6 months and V15 of the combined contralateral glands and contralateral parotid at 12 months. Dysphagia at 6 months was best correlated with V55-V60 of the superior pharyngeal constrictors. It was shown that all the examined NTCP models could fit the clinical data well with very similar accuracy. Statistically significant NTCP thresholds could be identified for each model for the respective organs and clinical endpoint cases. OC-0512 MR imaging predictor of survival in pediatric ependymoma patients after radiotherapy F. Tensaouti 1 , A.D. Ducassou 2 , L.C. Chaltiel 3 , A.S. Sevely 4 , S.B. Bolle 5 , X.M. Muracciole 6 , B.C.D. Coche- Dequant 7 , C.A. Alapetite 8 , S.S. Supiot 9 , A.H. Huchet 10 , V.B. Bernier 11 , L.C. Claude 12 , A.I.B.S. Bertozzi-Salamon 13 , P.P. Péran 14 , P.P. Payoux 15 , A.L. Laprie 16 1 ToNIC- Toulouse NeuroImaging Center- Université de Toulouse- Inserm- UPS-, ToNIC- Toulouse NeuroImaging Center- Université de Toulouse- Inserm- UPS-, Toulouse, France 2 Department of Radiation Oncology- Institut Claudius Regaud- Institut Universitaire du Cancer de Toulouse – Oncopole- Toulouse- France, Radiation Oncology, Toulouse, France 3 Department of Biostatistics- Institut Claudius Regaud- Institut Universitaire du Cancer de Toulouse-Oncopole- Toulouse- France, Department of Biostatistics, Toulouse, France 4 Department of Radiology- CHU Purpan- Toulouse- France, Department of Radiology, Toulouse, France 5 Department of Radiation Oncology- Institut Gustave Roussy- Paris- France, Department of Radiation Oncology, Paris, France 6 Department of Radiation Oncology- CHU La Timone- Marseille- France, Department of Radiation Oncology-, Proffered Papers: CNS