ESTRO 38 Abstract book

S459 ESTRO 38

radiotherapy in our institution between April 2003 and April 2017. We registered age, sex, location of primary tumour, extent of resection, histological grade, radiation dose to tumour bed, boost dose to residual tumour and radiation technique. We have follow-up data of all patients, having also registered date of first relapse, date of death and/or date of last follow-up. We divided patients in 4 groups according to radiotherapy target volumes: surgical bed in patients with complete resection (n=6), surgical bed plus boost to residual tumour (n=12), residual tumour only (n=4) and tumour bed without boost in one patient with residual tumour. We then compared OS, DFS and LC only for the first two groups using the Kaplan-Meier method. For age and radiotherapy dose, Cox univariate analysis was applied. Results Median follow-up was 4.2 years. The characteristics of the patients are summarized in table 1. Of all 23 patients, 18 of them were alive at the moment of last follow-up, 14 of which were free of disease. 2 patients presented distant failure and 7 patients presented local relapse. We observed non-significant differences in OS, DFS and LC between the complete resection group and the boost group. 2-year OS was 100% and 100% respectively, DFS 100% and 91.7% respectively and LC 100% and 91.7% respectively. 4-year OS was 100% and 87.5% respectively, DFS 100% and 80.2% respectively and LC 100% and 91.7% respectively. We observed statistically significant differences only in DFS for histological grade, response to upfront treatment and age.

showed a trend of lower disease-free survival rate in Kaplan-Meier survival curves (p=0.12) when compared to irradiation to whole ventricle, whole brain, or cranial spinal area. There is no disease-free survival difference in risk factors analysis in univariate Cox proportional hazards models, including age, metastatic status at diagnosis, tumor diameter, chemotherapy, and βHCG detection. Patients who received irradiation only to whole ventricle showed lower treatment toxicity and better quality of life during follow-up compared to irradiation to whole brain and cranial spinal area.

Conclusion Our results showed excellent disease-free survival and high rate of success of salvage treatment among pediatric basal ganglia germinomas after radiotherapy with or without chemotherapy. Focal irradiation showed a trend of lower disease-free survival, and whole ventricle irradiation showed lower treatment toxicity and better quality of life. PO-0871 Efficacy of radiotherapy boost in incompletely resected paediatric ependymoma: a retrospective study M. Ramos Albiac 1 , B. Gutiérrez 1 , N. Mestre 2 , M. Mota- Foix 3 , S. Pérez-Hoyos 3 , A. Llort 4 , P. Cano 5 , J. Giralt 1 1 Hospital Universitario Vall d'Hebron, Radiation Oncology Department, Barcelona, Spain ; 2 Centro de Regulación Genómica, Centro de Regulación Genómica, Barcelona, Spain ; 3 Vall d'Hebron Institut de Recerca, Unitat d'Estadística i Bioinformàtica, Barcelona, Spain ; 4 Hospital Universitario Vall d'Hebron, Pediatric Oncology, Barcelona, Spain ; 5 Hospital Universitario Vall d'Hebron, Neurosurgery, Barcelona, Spain Purpose or Objective The main objective of the study is to determine whether a radiotherapy boost to residual tumour in incompletely resected paediatric ependymoma confers the same local control (LC) and overall survival (OS) than a complete resection. Material and Methods We retrospectively analyzed 23 patients diagnosed with ependymoma and treated with upfront post-operative