RO-08. THE EFFECTIVENESS AND SAFETY OF PBT IN CHILDREN WITH MALIGNANT CENTRAL NERVOUS SYSTEM (CNS) TUMOURS: A SYSTEMATIC REVIEW Caroline Main1, Simon P. Stevens1, Nicky Thorp2, Roger E. Taylor3, Madhumita Dandapani4, Mark G. Pritchard5, Rachel Dodds6, Keith Wheatley1, Pamela R. Kearns1,4, Barry Pizer7, Bob Phillips6,8, Matthew C.H.J. Morrall6, Martin English4, Sophie Wilne9, and Jayne S. Wilson1; Cancer Research UK Clinical Trials Unit, University of Birmingham, UK; The Clatterbridge Cancer Centre, Liverpool, UK; College of Medicine, Swansea University, UK; Birmingham Children’s Hospital NHS Foundation Trust, Birmingham, UK; Royal Stoke University Hospital, Stroke-on-Trent, UK; Leeds General Infirmary, Leeds, UK; Alder Hey Children’s NHS Foundation Trust, Liverpool, UK; Centre for Reviews and Dissemination (CRD);, University of York, UK; Queen’s Medical Centre, Nottingham, UK OBJECTIVES: To assess the clinical effects of PBT for the treatment of children with malignant CNS tumours. METHODS: Eleven electronic databases were searched from1985 onwards.Comparative andnon-comparative studies were included. Outcomes included overall survival (OS), local/distant relapse rates (LRR and DRR), toxicities, neurocognitive outcomes and quality of survival. Standard systematic review methods were used to minimise bias in study identification, selectionanddataextraction.RESULTS:Seventeen studieswith 492 patients (pts) were included. Mean sample size was 29 (range: 6-109) with mean follow-up of 3.1 years (range: 0.1-11.7). Studies were in: low grade glioma [n 1⁄4 3, pts 1⁄4 65; OS: 83%-100% (follow-up: 2.0-7.6 years); 3-year LRR: 0%]; ependymoma [n 1⁄4 3 pts 1⁄4 91; OS: 79%-100% (follow-up: 2.2-3.0 years); LRR: 0%-46% (follow-up: 2.2-5.0 years); DRR: 17%-33% (follow-up: 3.0-5.0 years)]; medulloblastoma/primitive neuroectodermal tumours (PNET’s) (n 1⁄4 5, pts 1⁄4 211; OS: 81%-86% (follow-up: 3.0-7.0 years); LRR: 0%-15% (follow-up: 3.2-7.0 years); DRR: 24% at 7.0-years]; atypical teratoid rhabdoid tumours (AT/RT) [n 1⁄4 5, pts 1⁄4 76; OS: 53%-90% (follow-up: 2.0-3.2 years); LRR: 0%-20% and DRR: 20%-40% (follow-up: 2.3-3.2 years)]; germ cell tumour [n 1⁄4 1, pts 1⁄4 22; OS: 100%; LRR: 0%; DRR: 4.5% (follow-up: 2.3 years)]; pineoblastoma [n 1⁄4 1, pts 1⁄4 11; LRR and DRR both 9% at 1.7-years]. Adverse late effects reported were ototoxicity (9%-21%),neuro-endocrinopathies (3%-63%), growthproblems and neurocognitive deficits. CONCLUSIONS: The limited quantity and quality of evidence suggests PBT probably achieves similar OS and LRR as historic photon cohorts, whilst having a similar or reduced mid-late toxicity profile. However, this is subject to substantial uncertainty due to limited longterm outcome data and no controlled evidence. Neuro-Oncology 18:iii159–iii164, 2016. doi:10.1093/neuonc/now082.8 #The Author(s) 2016. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.