ESTRO 37 Abstract book

ESTRO 37

S440

many paediatric tumours. The number of proton centres operating worldwide is currently expanding rapidly and the number of children and types of tumours treated with protons is expected to increase. The present survey aims to describe the current patterns of care of children and adolescents treated with protons in Europe. Material and Methods All proton centres in operation in Europe in 2016 were invited to participate between July and October 2017. Through a standardized questionnaire, non-identifiable grouped data were collected for patients aged less than 22 years, including age groups, diagnoses, proton delivery techniques and information about the organization of the long-term follow-up of patients. Results As of October 2017, 6 out of the 11 operating centres (excluding eye proton therapy facilities) had responded. These centres were located in France (1), Germany (2), Italy (1), Sweden (1) and Switzerland (1). In these centres, a total of 392 children were treated with protons in 2016, of whom 60% were treated with pencil beam scanning and 40% with passive scattering. The percentage of paediatric patients aged less than 5 years was 31% (range, 16-38), and 58% (range, 34-68) were aged less than 10 years. CNS tumours accounted for 62% (range, 43- 84) of the diagnoses, with ependymoma (15%), medulloblastoma (13%), craniopharyngioma (8%) and low grade glioma (6%) being the most frequent histological types. Other head and neck tumours accounted for 9% (range, 3-12) of diagnoses. Non-skull base bone or soft tissues sarcoma accounted for 25% (range, 13-32) of cases. Long-term follow-up by radiation or paediatric oncologists was typically scheduled on an annual basis, for at least 5 to 10 years, even though recommendations exist for lifelong follow-up. Conclusion This is the first survey to describe patterns of proton therapy use in Europe in children. We found that proton therapy is already being used to treat a fair number of cancer diagnoses in children, with different techniques of proton delivery, most commonly in very young children affected by solid tumours. The study will be extended to other European proton centres, and compared to patterns of care in North America and Asia where we are currently conducting the same survey. PO-0843 Outcomes of paediatric diffuse intrinsic pontine gliomas treated with hypofractionated radiotherapy A. Shiarli 1 , G. Smyth 1,2 , F. Carcellar 3 , S. Vaidya 3 , L. Marshall 3 , S. Zacharoulis 3 , K. Powell 3 , L. Conti 3 , D. Frost 1 , F. Saran 1,3 , H. Mandeville HC 1,3 1 The Royal Marsden NHS Foundation Trust- Sutton- UK, Department of Radiotherapy, Sutton, United Kingdom 2 The Institute of Cancer Research, Department of Radiotherapy, Sutton, United Kingdom 3 The Royal Marsden NHS Foundation Trust- Sutton- UK, The Children’s and Young People’s Unit, Sutton, United Kingdom Purpose or Objective DIPG is a rare paediatric brain tumour with a very poor prognosis; median survival is approximately 9 months(m), <10% survive two years(y). Data suggests hypofractionated radiotherapy (RT) produces comparable outcomes to 54Gy in 30 fractions. In 2012 at The Royal Marsden Hospital (RMH) 39Gy in 13 fractions was adopted as standard of care. Low dose reirradiation 20Gy in 10 fractions has also been implemented for those with a response to initial RT of >3m. We have undertaken to report the outcomes of DIPG treated with a strategy of hypofractionated radiotherapy, followed by reirradiation at relapse for good responders. Material and Methods

Conclusion The use of VMAT technique is associated with less radiation doses to the remaining kidney and better coverage to the PTV than 3D-CRT technique for WAI, with preliminary clinical experience showing favorable toxicity profile. Long-term results from prospective studies might prove the ability of VMAT to spare renal function in the setting of WT treatment. PO-0842 Proton Therapy in children, adolescents and young adults: Patterns of care survey in Europe N. Journy 1 , R. Kleinerman 2 , C. Alapetite 3 , V. Bernier- Chastagner 4 , R. Dendale 3 , S. Bolle 3 , J. Doyen 5 , K. Gurtner 6 , J.L. Habrand 7 , S. Helfre 3 , M. Hoyer 8 , M. Krause 6 , J. Maduro 9 , P.W. Nyström 10 , B. Rombi 11 , B. Timmermann 12 , F. De Vathaire 1 , D.C. Weber 13 , D. Indelicato 14 , A. Berrington de Gonzalez 2 1 National Institute for Health and Medical Research, CESP U1018, Villejuif, France 2 NIH / DHHS / National Cancer Institute, Division of Cancer Epidemiology and Genetics- Radiation Epidemiology Branch, Bethesda, USA 3 Curie Institute, Institut Curie - Proton Therapy Center, Orsay, France 4 Institut de Cancérologie de Lorraine, Department of Radiotherapy, Vandoeuvre-les-Nancy, France 5 Antoine-Lacassagne Centre, Department of Radiotherapy, Nice, France 6 University Hospital Carl Gustav Carus, University Proton Therapy Dresden, Dresden, Germany 7 Centre François Baclesse, Advanced Resource Center for HADrontherapy / Department of Radiation Oncology, Caen, France 8 Aarhus University Hopital, Danish Center for Particle Therapy, Aarhus, Denmark 9 University of Groningen, University Medical Center Groningen, Groningen, The Netherlands 10 Uppsala University Hospital, The Skandion Clinic, Uppsala, Sweden 11 Azienda Provinciale per i Servizi Sanitari, Proton Therapy Center, Trento, Italy 12 University Hospital Essen, Clinic for Particle Therapy / West German Proton Therapy Center Essen / West German Cancer Center, Essen, Germany 13 Paul Scherrer Institute, Center for Proton Therapy, Villigen, Switzerland 14 University of Florida, Department of Radiation Oncology / Proton Therapy Institute, Jacksonville- FL, USA Purpose or Objective Children are especially prone to late side effects of normal tissue irradiation. As such, proton therapy is considered an optimal radiation modality for treating