ESTRO 38 Abstract book

S84 ESTRO 38

evaluate middle-term and long term toxicity. Efficiency will be reported as soon as data are available.

GATE - UMR 5824-CNRS, Lyon, France; 9 Centre Léon Bérard, Radiotherapy, Lyon, France ; 10 Institut de Cancérologie de l'Ouest, Radiotherapy, Nantes, France Purpose or Objective Hypofractionated Stereotactic Body Radiation Therapy (SBRT) is demonstrated as safe and efficient in many adult situations, including mainly primary/secondary tumors in brain, spine, and lung or in case of re-irradiation (re-RT). In pediatric situations, data are rare and needed to assess feasibility, efficiency and acute/long term toxicitiesin patients (pts) with radioresistant cancers (sarcomas, brain tumors such as ependymomas) or for re-RT. A multicentric national prospective study considering SBRT in young pts (1.5-20 y.) was opened in 12/2013, with multi-disciplinary staff confirmed indication of SBRT. Material and Methods The study was built as a prospective cohort study with several arms considering the site of lesion, summarized in Fig. 1. Only pts with ependymomas in relapse after radiotherapy (RT) could be included after complete surgery while the others had no surgery or incomplete macroscopic tumor resection. The main objective was to evaluate the 6-months local control (RECIST 1.1). Secondary objectives were to evaluate the feasibility of SBRT in childhood, 3-months, 1 and 2-years local control rates, acute, and middle-term toxicities (3-24 months) using NCI CTC v 4.0 criteria. Long-term toxicity will be evaluated using the national cohort study PEDIART.

Proffered Papers: BT 2: Cervix brachytherapy

OC-0172 Performance of ring vs ovoids and intracavitary vs intracavitary-interstitial in the EMBRACE study M. Serban 1 , C. Kirisits 2 , A. De Leeuw 3 , R. Pötter 2 , I.M. Jürgenliemk-Schulz 3 , N. Nesvacil 2 , J. Swamidas 4 , R. Hudej 5 , G. Lowe 6 , T.P. Hellebust 7 , G. Menon 8 , A. Oinam 9 , P. Bownes 10 , B. Oosterveld 11 , M. De Brabandere 12 , K. Koedooder 13 , A.B.L. Marthinsen 14 , D. Whitney 15 , J. Lindegaard 1 , K. Tanderup 1 1 Aarhus University Hospital, Department of Oncology, Aarhus, Denmark; 2 Medical University of Vienna / General Hospital of Vienna- Vienna- Austria, Department of Radiation Oncology, Vienna, Austria ; 3 University Medical Centre Utrecht- The Netherlands, Department of Radiation Oncology, Utrecht, The Netherlands; 4 Tata Memorial Hospital- Mumbai- India, Department of Radiation Oncology, Mumbai, India; 5 Institute of Oncology Ljubljana- Slovenia, Department of Radiotherapy, Ljubljana, Slovenia; 6 Mount Vernon Hospital- London- UK, Cancer Centre, London, United Kingdom; 7 The Norwegian Radium Hospital- Oslo University Hospital- Oslo- Norway, Department of Oncology, Oslo, Norway; 8 Cross Cancer Institute- University of Alberta- Edmonton- Canada, Department of Oncology, Edmonton, Canada; 9 Postgraduate Institute of Medical Education and Research- Chandigarh- India, Department of Radiotherapy and Oncology, Chandigarh, India; 10 St James's University Hospital- Leeds- UK, Leeds Cancer Centre, Leeds, United Kingdom; 11 Arnhem-The Netherlands,Radiotherapiegroep, Arnhem, The Netherlands; 12 UZ Leuven- Belgium, Department of Radiation Oncology, Leuven, Belgium; 13 Academic Medical Center- University of Amsterdam- Amsterdam- The Netherlands, Department of Radiation Oncology, Amsterdam, The Netherlands ; 14 Cancer Clinic- St. Olavs Hospital- and Department of Physics- NTNU- Trondheim- Norway, Department of Radiotherapy, Trondheim, Norway; 15 Cambridge University Hospitals NHS Foundation Trust- Addenbrooke's Hospital- Cambridge- UK, Oncology Centre, Cambridge, United Kingdom Purpose or Objective To investigate the influence of brachytherapy (BT) technique and applicator type on target dose coverage, isodose surface volumes, and dose to organs at risk (OARs). Material and Methods 949 patients treated with tandem/ovoids (T&O) and tandem/ring (T&R) BT applicators, from 18 centres in the EMBRACE study, were analysed. Patients received external beam radiotherapy with concomitant chemotherapy, followed by MRI guided adaptive brachytherapy with individualised dose prescription. Centres were divided into 4 groups, according to their applicator (T&O vs T&R) and intracavitary (IC) vs intracavitary/interstitial (IC/IS) usage: T&O and T&R IC centres treating mainly with the IC technique; T&O IC/IS and T&R IC/IS centres treating routinely with the IC/IS technique (>20% of patients). V85Gy EQD2 10 , CTV HR D 90% as well as bladder, rectum and vaginal (lateral point at 5mm with respect to the applicator) doses were evaluated. Data was analysed as independent samples based on Student's t-test or by multiple linear regression models. Results Patient characteristics, target and OAR doses for each center group are presented in Table 1. T&R IC compared to T&O IC centres had : mean CTV HR D 90% higher by 4.9Gy EQD2 10 for a CTV HR volume of 30cm 3 and no statistically significant difference when > 45cm 3 (Fig.1a); mean V85Gy

Results 48 pts were included in 10 institutions. 4 pts did finally not receive SBRT (, 1 for early progression, 1 pt refusal, 2 ptsdue to medical decision after inclusion) and were excluded from the analysis. Among the population analysis (n=44), the median age was 12 y. (min 3 – max 20).15 pts were irradiated in first intention: - 4 pts with brain lesions received a median dose of 32.5 Gy/5fr(isodose 80%)). - 5 pts with lung lesions received a median dose of 50 Gy/5 fr, (isodose 80%) - 6 pts with spine lesions received amedian dose of 50 Gy/5 fr, (isodose 80%) 29 pts were included for re-RT : - 12 pts were treated by post-operative SBRT forlocally relapsed ependymoma (median dose 25/5 fr., isodose 80%) - 17 pts were treated for re-RT in other situations (brain, spine, lung…) without surgery (median dose 25 Gy/5 fr). All the pts could receive SBRT. Median follow-up was 23 months (12-24). No pt required general anesthesia. Considering acute toxicity (< 3 months after SBRT), 1 pt reported epilepsy (grade 3). Grade 2 toxicitywas observed in 3 pts (asthenia, transitory radiation pneumonitis, headache). Middle term RT toxicity (Grade > 2, 3-24 months after SBRT) was identified for 1 pt (pyloric spasm after spinal SBRT). Conclusion SBRT is feasible and safe in childhood, considering acute toxicity in brain, lung and spine treatment or in selected cases of re-RT. More follow-up is needed to better