Preoperative speech deficits in children with posterior fossa tumours (PFTs) may be linked to postoperative speech impairment (POSI), a hallmark of posterior fossa syndrome, yet this relationship remains underexplored. POSI is characterized by mutism or markedly reduced speech that resolves within weeks to months but often leaves persistent motor-speech deficits. Most existing literature has focused on postoperative outcomes, with limited attention to preoperative speech function. We therefore systematically investigated this association by analyzing perceptible motor-speech features in a large cohort of patients scheduled for surgery within the European Study of Cerebellar Mutism Syndrome. We included data from 135 children which formed three age-and sex- comparable groups: 16 patients who later developed POSI, 11 were mute and five had severely reduced speech (3;9–14;4 years), 62 patients with habitual speech (3;2–17;11 years), and 57 healthy controls (3;0–18;1 years). Patients were Italian-, Dutch-, and English-speaking, while controls were Dutch- and Italian-speaking. Four speech-language therapists rated participants’ narrative recordings on 23 speech features (e.g., distorted vowels, imprecise consonants, stuttering, and hoarseness). Group comparisons revealed significant preoperative differences between the children who later developed POSI and the children with habitual speech in both hypernasality and in phonation-respiration (e.g., leaky, hoarse, and strained voice). In addition, patients who later developed POSI showed impairment compared to healthy controls in prosody (e.g., speech rate, excess and equal stress) and articulation (e.g., distorted vowels, imprecise consonants, sequencing errors). Patients with habitual speech differed from the controls in hypernasality and prosody. Moreover, age influenced the severity of articulatory and prosodic symptoms, with younger patients showing greater impairment. Children with PFT show signs of speech impairment preoperatively relative to healthy controls. When comparing patients, those later developing POSI show more severe impairments related to resonance and voice quality. This suggests possible differences in the degree to which speech-related underlying anatomical substrates were compromised, and these early differences may represent potential predictors of later POSI. These findings highlight the value of preoperative assessment for identifying children at a heightened risk of POSI, opening opportunities for prehabilitation - targeted early intervention in the form of speech therapy - to strengthen the speech-motor networks.

Posterior Fossa Syndrome is a common complication in children following posterior fossa tumour surgery, typically marked by transient postoperative speech impairment (POSI; i.e., mutism or reduced speech). Previous studies suggest that children who develop POSI show different language profiles postoperatively compared to those who do not. It remains unclear to what extent these language difficulties exist preoperatively and whether preoperative language difficulties are related to postoperative speech status. This study provides the first comprehensive analysis of preoperative language samples, using data from the European study of Cerebellar Mutism Syndrome. Patients with and without POSI were compared to identify preoperative language characteristics that may be associated with POSI. Preoperative language samples of 34 patients aged 3–16 years were analysed (16 developed POSI; 18 did not). We compared global sample characteristics and language performance across four levels: the semantic, lexical, morphosyntactic, and phonological level. No significant preoperative language differences were found between the groups for the four levels of language processing (all p-values > 0.137). Children who developed POSI produced more unintelligible speech preoperatively (β = -14.455, p = .024), with better intelligibility related to older age (age×group: β = 0.152, p = .007), only for the group with POSI. While the main focus of this study was on language, these findings suggest that risk factors for POSI within the domain of verbal output may lie more in preoperative speech. A comprehensive analysis of preoperative speech may provide valuable insight into speech characteristics potentially related to POSI.

BACKGROUND:Word finding - the ability to retrieve and produce appropriate words in response to prompts or visual stimuli - is impaired in some patients with a posterior fossa tumour. Yet, few studies use preoperative assessment as a baseline, and an in-depth linguistic analysis of tasks assessing word-finding ability remains limited. The current study aims to fill this knowledge gap by analysing pre- and postoperative word-finding ability and identifying its linguistic predictors. METHOD:38 English-speaking patients (19 males and 19 females), aged between 2,5 and 17,6 years and diagnosed with posterior fossa tumours were assessed before and after surgery. Performance was assessed using a picture-naming task, Wordrace, measuring both accuracy and reaction times. These measures were interpreted in terms of their correlation with linguistic levels (i.e., lexical, semantic, phonological). RESULTS:Patients exhibited a significant slowing in word-finding speed following surgery, while accuracy remained stable across assessment points. Despite this decline in speed, we did not find evidence for a change in the influence of psycholinguistic factors on word-finding ability in our sample. Lexical-semantic variables predicted word-finding speed, whereas accuracy was influenced only by lexical variables. CONCLUSION:The findings suggest that although general performance declined postoperatively, we did not find evidence in our sample of disruption to the underlying linguistic processes engaged during word-finding. However, the absence of control group limits interpretation, and future studies comparing patients with healthy controls may reveal more subtle differences. The study emphasises the importance of longitudinal assessment in patients with posterior fossa tumours and future studies should incorporate additional timepoints to examine the potential effects of radiotherapy and chemotherapy on word-finding over time.

Abstract Purpose Ataxia is the most prevalent motor impairment in children following surgical resection of posterior fossa tumour. The aim of this study was to examine the prevalence, severity, trajectory and risk factors for ataxia in children following surgical resection of posterior fossa tumours. Methods Prospective observational multicentre cohort study, including children (aged < 18 years) undergoing surgical resection of a posterior fossa tumour in 36 European centres across 15 countries. Children were assessed using two ataxia scales; the Brief ataxia rating scale (BARS) and the Scale for the assessment and rating of ataxia (SARA). Assessments were undertaken pre-operatively, post-operative follow up 1 (2-weeks), post-operative follow up 2 (2-months) and post-operative follow up 3 (1-year) after surgery. Results 756 participants who underwent initial surgical management participated in the study, and 122 completed BARS assessment at all timepoints. In this group of children, ataxia was present in 40 (32.8%) participants pre-operatively, and 49 (40.2%) at post-operative follow up 1. Over 90% of participants demonstrated independent walking by 1 year post-operatively (defined by BARS/SARA gait item ≤3). Children with medulloblastomas and post-operative mutism demonstrated more severe ataxia compared to the remaining children. Conclusion Pre-operative ataxia, medulloblastoma and postoperative mutism were identified as the strongest predictors of persistent ataxia. Pre-operative ataxia has been identified for the first time as an indicator of long-term ataxia. This knowledge could be used to identify potential rehabilitation needs and highlights the benefits of an MDT pre-operative assessment.

Background Elastomeric devices (EDs) allow infusion of antibiotic via an intravenous catheter over 24 hours, supporting outpatient parenteral antimicrobial therapy. We conducted a systematic review of these devices in a paediatric population.Methods Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology was used to review studies assessing antibiotic delivery through EDs in a paediatric population (0-21 years). Medline, Embase, CINAHL, PubMed, The Cochrane Clinical Trials Library, ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform were searched.Results After deduplication, 1789 titles and abstracts were screened; 45 underwent full-text review and nine were suitable for qualitative synthesis. 567 patients were treated in 657 episodes. 14 different antibiotics and aciclovir were delivered through EDs, primarily 24-hour infusions. Median treatment duration was 10 to 15 days. A variety of infections were treated (mostly infective exacerbations of cystic fibrosis (CF), bone/joint infection). Efficacy data were limited; two studies demonstrated non-inferiority of antibiotic therapy via ED for CF patients compared with conventional infusion pumps. In another study, only two patients (6%) experienced treatment failure. Few adverse events were reported: 1 of 34 patients (3%) experienced ED failure due to misplacement of the central line; one case of antibiotic crystallisation.Conclusion EDs have been used for a range of antimicrobial agents in children, in the treatment of a variety of infections, mostly in CF patients, and few adverse events were reported. Further studies should concentrate on new patient groups, and specific information about safety and cost effectiveness of ED in children is required.PROSPERO registration number CRD42021237146.

Abstract Background Embryonal tumor with multilayered rosettes (ETMR) is a rare, highly aggressive central nervous system embryonal tumor primarily affecting infants and young children, with poor outcomes despite intensive multimodality therapy. Retrospective data are limited by heterogeneous regimens and small cohorts, complicating reliable insights. To overcome these challenges, PNOC031 was developed through global collaboration among neuro-oncologists across continents (North America, Europe, Australia). This effort addresses inherent difficulties in designing trials for this rare tumor, tailoring treatments to individual patient needs, clarifying optimal timing and integration of radiotherapy and high-dose chemotherapy (HDC) with stem cell rescue, and establishing robust correlative studies with biomarkers for risk stratification and future therapy guidance. Methods This pragmatic, multi-cohort platform trial standardizes frontline care for newly diagnosed patients, including maximal safe resection, uniform IRS-III induction chemotherapy, and proactive intrathecal/intraventricular therapy. Radiation-eligible patients are randomized to early or late radiotherapy arms incorporating HDC where appropriate. Radiation-ineligible infants receive HDC-based therapy, while metastatic cases follow physician-directed regimens within trial backbones. Longitudinal biospecimens, neurocognitive/quality-of-life assessments, and outcomes are collected. The trial is currently opening and enrolling globally. Aims Primary: Independently evaluate 6-month progression-free survival (PFS) in each radiotherapy arm against historical radiation-sparing HDC controls. Secondary: Assess safety, feasibility, relapse patterns, and functional/quality-of-life outcomes across cohorts; correlate biomarkers with treatment response and relapse risk. Correlative Studies Comprehensive tumor analyses (whole-genome/exome seq, [single cell]RNA-seq, DNA methylation) and liquid biomarkers (e.g., circulating miR517a in blood/CSF) aim to identify genomic drivers, resistance mechanisms, and tools for real-time disease monitoring, early relapse detection, and risk-adapted therapeutic strategies. Conclusions PNOC031 exemplifies the strong commitment of global experts to collaboratively tackle complex clinical questions in rare pediatric cancers, generating standardized prospective data that fosters cross-trial aggregation and drives meaningful advancements toward personalized, effective care for this devastating disease.

Abstract Purpose Childhood brain tumour survival rates in developing countries remain low (20–30%) compared to approximately 80% in developed nations, underscoring major disparities in care. To determine the outcomes, and quality of life at 12-week follow-up in children aged 1-17 years diagnosed with Central Nervous System (CNS) tumours at Korle Bu Teaching Hospital (KBTH). Methods Hospital-based prospective, observational study using the PedsQL questionnaire at the initial presentation and 12 weeks follow-up. The study included children aged 1–17 years with newly diagnosed, radiologically confirmed CNS tumours, along with their caregivers, who attended the Pediatric Oncology and Neurosurgery Units at KBTH over 13-month period. Results The study included 45 children (median age 7 years), with 56% male. Infratentorial tumours were most common (45%), and low-grade gliomas were the predominant histology. Nineteen children (42%) received definitive surgical treatment, with only four children (9%) receiving gross total resection (GTR) with median time to GTR of 28.5 days (range 27.5-37 days). Twelve-week survival was 68.9%. There was a strong correlation between parent-proxy and child self-reported total PedsQL scores (r = 0.890; P < 0.001) (95%CI 3.10 to 9.93) at presentation. Baseline PedsQL scores were significantly lower in children who died within 12 weeks (median 33.8) versus survivors (median 49.0; p = 0.0011). At follow-up, children’s self-reports of emotional well-being were lower than caregivers’ assessments. Conclusion The high mortality rate at 12 weeks is a significant concern and needs to be addressed. In this study, low QoL at presentation was associated with early mortality. Quality of life improved significantly at 12 weeks, though caregivers often underestimated their children’s emotional difficulties. 1. Moreira DC, Rajagopal R, Navarro-Martin del Campo RM, et al. Bridging the gap in access to care for children with CNS tumors worldwide. JCO Glob Oncol. 2020;6:583-584. doi:10.1200/GO.20.00047 2. National Cancer Institute. Cancer stat facts: Brain and other nervous system cancer (including pediatric data). Surveillance, Epidemiology, and End Results (SEER) Program. Accessed July 21, 2025. https://seer.cancer.gov/statfacts/html/brain.html

Rare paediatric central nervous system (CNS) tumours comprise a biologically-heterogeneous group of low-incidence diseases that present significant challenges to both therapeutic development and clinical research, limiting the availability of high-quality evidence to guide clinical care. The UK3CR Children’s Cancer Research Group (CRG) CNS Tumours Subgroup convened a multidisciplinary workshop to identify research priorities and establish a strategic framework for advancing clinical trials in this setting. Four high-priority tumour groups—craniopharyngioma, choroid plexus carcinoma (CPC), very high-risk medulloblastoma (VHR-MB), and rare embryonal and sarcomatous tumours (REST), including embryonal tumour with multilayered rosettes (ETMR)—were evaluated. Key outcomes included the feasibility of a UK-led craniopharyngioma trial, the need for enhanced national CPC data collection, and support for European early-phase platform trials in VHR-MB. REST highlighted transnational regulatory complexity requiring coordinated registries and parallel trial models. Cross-cutting barriers included regulatory discordance, contracting delays, fragmented funding, pharmacovigilance differences, data-sharing constraints, and interoperable infrastructures. The workshop emphasised innovative methodologies, including Bayesian/adaptive designs, platform trials, and external control arms, to maximise efficiency in small populations, alongside strengthened patient involvement and international collaboration. Collectively, these findings define a collaborative and internationally-aligned strategic roadmap to accelerate clinical research and improve outcomes in rare paediatric CNS tumours.

Postoperative cerebellar mutism syndrome (pCMS) is a recognised complication following posterior fossa tumour (PFT) resection in children, marked by delayed-onset mutism or reduced speech with neurocognitive and motor deficits. Injury to proximal efferent cerebellar pathways is implicated. This study evaluates the impact of modified surgical techniques and experience on pCMS incidence over 17 years at a single tertiary centre. We retrospectively reviewed 176 PFT resections in 167 patients (age 0–18) from 2007 to 2023. Surgical modifications from 2016 aimed to reduce pCMS risk and included reduced CUSA use, avoidance of transvermian approaches, limited cerebellar retraction, and preoperative risk stratification via the Rotterdam pCMS score. pCMS was classified as grade 1 (mutism) or grade 2 (reduced speech). Overall pCMS incidence was 17.6

Purpose Preoperative speech deficits may be linked to postoperative speech impairment (POSI), a hallmark of posterior fossa syndrome, yet this relationship remains underexplored. POSI is characterized by mutism or markedly reduced speech that resolves within weeks to months but often leaves persistent motor-speech deficits. Most existing literature has focused on postoperative outcomes, with limited attention to preoperative speech function. We therefore systematically investigated this association by analyzing perceptible motor-speech features in a large cohort of patients scheduled for surgery within the European Study of Cerebellar Mutism Syndrome. Method We included data from 135 children which formed three age-and sex- comparable groups: 16 patients who later developed POSI, 11 were mute and five had severely reduced speech (3;9–14;4 years), 62 patients with habitual speech (3;2–17;11 years), and 57 healthy controls (3;0–18;1 years). Patients were Italian-, Dutch-, and English-speaking, while controls were Dutch- and Italian-speaking. Four speech-language therapists rated participants’ narrative recordings on 23 speech features (e.g., distorted vowels, imprecise consonants, stuttering, and hoarseness). Results Group comparisons revealed significant preoperative differences between the children who later developed POSI and the children with habitual speech in both hypernasality and in phonation-respiration (e.g., leaky, hoarse, and strained voice). In addition, patients who later developed POSI showed impairment compared to healthy controls in prosody (e.g., speech rate, excess and equal stress) and articulation (e.g., distorted vowels, imprecise consonants, sequencing errors). Patients with habitual speech differed from the controls in hypernasality and prosody. Moreover, age influenced the severity of articulatory and prosodic symptoms, with younger patients showing greater impairment. Conclusion Children with PFT show signs of speech impairment preoperatively relative to healthy controls. When comparing patients, those later developing POSI show more severe impairments related to resonance and voice quality. This suggests possible differences in the degree to which speech-related underlying anatomical substrates were compromised, and these early differences may represent potential predictors of later POSI. These findings highlight the value of preoperative assessment for identifying children at a heightened risk of POSI, opening opportunities for prehabilitation - targeted early intervention in the form of speech therapy - to strengthen the speech-motor networks.

Postoperative speech impairment (POSI) is a core symptom of cerebellar mutism syndrome (CMS) and is a common complication after the resection of paediatric posterior fossa (PF) tumours. Preoperative glucocorticoids (pGC) are considered standard treatment to reduce tumour oedema; in addition, glucocorticoids are often administered intraoperatively (iGC) to reduce both postoperative nausea and vomiting. The study aims to investigate whether the occurrence of POSI may be associated with pGC and iGC. In a prospective observational multicentre study, we included children with a PF tumour requiring either resection or open biopsy. The use of pGC and iGC, including drug type and dose, was registered. Postoperative speech status was classified as mutism, reduced speech, or habitual speech, where mutism and reduced speech were considered POSI of higher and lower severity, respectively. Proportional odds logistic regression with adjustment for tumour type, tumour location, and age was used to analyse the occurrence of POSI associated with glucocorticoids (GC). From August 2014 to November 2024, we recruited 810 children, of whom 605 were included in the primary analysis. We found no association between the use of GC (pGC nor iGC) and the occurrence of POSI. The result did not change when adjusting for tumour type, tumour location, and age. The analysis included both a comparison between using and not using pGC (OR 1.06 [95

Neuroblastoma is a highly metastatic paediatric malignancy with poor prognosis, and remains a leading cause of paediatric cancer mortality. Current risk stratification is disproportionately reliant on MYCN amplification, a feature present in only ∼25% of cases. This narrow focus neglects the majority of patients that have non- MYCN amplified tumours, limiting opportunities for therapeutic innovation. To define molecular drivers of metastasis in non -MYCN amplified neuroblastoma and identify putative prognostic markers, we leveraged our validated in vivo chick embryo xenograft model to profile oxygen-sensitive transcriptional changes, revealing a cohort of ∼400 genes associated with metastatic competence. Integrative survival analysis using two independent patient cohorts identified 59 genes predictive of event-free survival in non- MYCN amplified disease. Among these, the poorly characterized Zinc Finger DHHC-Type Palmitoyltransferase 23 (zDHHC23) emerged as a robust prognostic candidate. Proteomic interrogation of zDHHC23 under varying oxygen conditions uncovered dynamic interactome remodelling, notably hypoxia-attenuated association with the 26S proteasome and the TIM23 mitochondrial import complex. These findings suggest zDHHC23 as a hypoxia-responsive regulator linked to metastatic signalling, and a promising target for biomarker development and therapeutic intervention in high-risk, non-MYCN amplified neuroblastoma. ### Competing Interest Statement The authors have declared no competing interest. Biotechnology and Biological Sciences Research Council, https://ror.org/00cwqg982, BB/R000182/1, BB/M012557/1 Medical Research Council, MR/K015931/1 Alder Hey Children's NHS Foundation Trust, TF8838 University of Liverpool, https://ror.org/04xs57h96

Cerebellar Mutism Syndrome (CMS) is a neurological complication of posterior fossa (PF) tumour surgery in children, and postoperative speech impairment (POSI) is the cardinal symptom of CMS. The role of tumour volume on the risk of POSI remains unexplored. This study investigates the association between tumour volume and the risk of POSI. We included 360 patients from the European CMS study with available preoperative T1-weighted contrast-enhanced brain MRI. Speech status was assessed within two weeks postoperatively and categorised into three levels: habitual speech, severely reduced speech, and mutism. Tumour volumes were calculated using the BrainLab Elements SmartBrush™, a semi-automated segmentation tool. We used proportional odds models to estimate the odds ratio (OR) with adjustments for tumour location, pathology, and age. Based on the primary analysis, a risk stratification model for medulloblastoma patients was constructed, and the optimal volume cut-off was determined with Youden's Index. We found no effect of the overall tumour volume on the risk of POSI. This result did not change when adjusted for tumour location, pathology, and age. We found an association between tumour volume of medulloblastoma and the risk of POSI (unadjusted OR of 1.04 per increase in cm3 (95% CI 1.01;1.07, p = 0.01)), which did not change when adjusting for tumour location and age. The risk stratification cut-off for the tumour volume of medulloblastoma was calculated to be 16,5 cm3. Patients with medulloblastoma and preoperative tumour volumes below 16,5 cm3 had an absolute risk of 13% for POSI (low-risk group), whereas patients with preoperative tumour volumes above 16,5 cm3 had an absolute risk of 50% for POSI (high-risk group). Our data showed an association between preoperative tumour volume and the risk of POSI in children with medulloblastoma, while no association was found for the volume of other tumour types. We suggest a straightforward cut-off risk model for assessing the risk of POSI in children with medulloblastoma based on preoperative tumour volume. This approach can aid clinicians in informing patients and parents about the complications related to CMS following PF tumour surgery in children. ID NCT02300766 (October 2014).

Paediatric tumours of the pineal region are rare CNS tumours accounting for 3% of brain tumours in children and adolescents; the majority of which are germ cell tumours. This review focuses on pineal parenchymal tumours (pineoblastoma, pineal parenchymal tumour of intermediate differentiation, pineocytoma) and those specifically arising in the pineal region (papillary tumours of the pineal region, desmoplastic myxoid tumour of the pineal region, SMARCB1-mutant and pineal cyst), which together account for up to a third of pineal tumours. In recent years, the diagnostic classification of these specific tumour-types has been refined by the integration of molecular pathology. Given the differences in grade, tumour biology and clinical behaviour, an accurate integrated neuropathological diagnosis is essential in deciding an appropriate treatment strategy which can range from surgery only to intensive multi-modal therapies. The most common of these tumours in children is WHO Grade 4 pineoblastoma, where specific molecular subgroups occurring in very young patients are difficult to treat successfully. Further challenges include the anatomical position and associated surgical risk together with a lack of molecularly annotated clinical data and consequent limited evidence to guide the therapeutic approach due to their rarity. These guidelines aim to provide a framework for diagnosis, prognostication and management based on current literature and expert opinion.

PURPOSE:European Reference Networks (ERN) are collaborative networks connecting healthcare professionals across Europe. A virtual multidisciplinary tumor board (VMTB) for children with central nervous system (CNS) tumors was established within the ERN for pediatric oncology (ERN PaedCan) in 2022. We report the experience with this new format. METHODS:A web-based questionnaire was distributed to physicians for cases presented between November 2022 and November 2023, addressing the implementation of provided recommendations, satisfaction and basic data about the local institution. Baseline information of the presented cases was taken from anonymized VMTB protocols. RESULTS:In the first year, 19 patients from 11 institutions located in nine European countries were discussed in 21 VMTB. The German national reference center for neuroradiology demonstrated MRI findings in 19/21 (91%) conferences. 19 questionnaires were answered by physicians from all participating countries. Main reason for VMTB presentation were questions about therapy (79%). Presenting institutions treated a median of 10 (5-150) neuro-oncological pediatric patients per year. All hospitals conducted own institutional tumor boards. National central review was available in 3/9 countries (33%). Recommendations were followed, at least partly, in all except one patient experiencing unexpected clinical deterioration. Recommendations were considered helpful in 90%. All participants would recommend the VMTB to colleagues. Technical issues regarding data provision were reported as the main obstacle in 56%. CONCLUSION:A European VMTB for pediatric patients with CNS tumors is feasible and perceived as useful by the participants. Recommendations were followed frequently. Optimization of privacy-compliant data exchange is crucial for continuance of the format.

To determine presentation, prediagnostic symptomatic interval (PSI), outcomes and quality of life at 12-week follow-up in children aged 1-17 years diagnosed with CNS tumours at Korle Bu Teaching Hospital (KBTH). This was a hospital-based cross-sectional, correlational study using the PedsQL questionnaire at the initial pre- sentation and 12 weeks after. The study population included all children (aged 1 to 17 years) with a new, ra- diologically diagnosed CNS tumour. and their caregivers attending the Paediatric Oncology and Neurosurgery Units of KBTH. The study included 45 children with a median age of 7 years (range 2-17 years) and 56% were males. The most common tumour location was infratentorial (45%) and low-grade gliomas were the most frequent histology (n=23). Common symptoms were headache (n=33), motor abnormalities (n=29) and vomiting (n=24). Two children had Neurofibromatosis type 1. The median diagnostic interval was 121 days (range 44-305 days), with a patient interval of 60 days and a pri- mary healthcare interval of 21 days. Nineteen children (42%) received definitive surgical treatment, with only four children (9%) receiving gross total resection, with a median time to resection of 28.5 days (range 27.5-37 days). Twelve-week survival was 68.9%. There was a strong correlation between caregivers’ and children’s total QOL scores at presentation (r=0.88). At follow-up, children’s self-reports of emotional well-being were lower than caregivers’ assessments. We have a high rate of mortality at 12 weeks and this needs to be addressed. Children with low-grade tumours experienced longer prediagnostic symptomatic intervals compared to those with high-grade tumours. There was a significant improvement in QOL at 12 weeks, but caregivers underestimated the emotional challenges their children faced. The study emphasizes the need for increased focus on the emotional well-being of children with CNS tumours and their survival.

Several treatment protocols are used for the treatment of high-risk medulloblastoma (HR-MB). In 2015, the UK Children's Cancer and Leukaemia Group issued guidance recommending treatment as per the SJMB03 protocol, whilst also recognising that the COG-99701 protocol maybe used. Patients were defined as high-risk if metastatic at presentation, large-cell/anaplastic histology, MYC amplification, significant residual disease or MYCN amplification. Recently, the latter two only define high risk if other adverse features are present. Methods: Retrospective multi-centre service evaluation of treatment of HR-MB at five UK centres. Patients were included if treated as per SJMB03 or COG-99701. Patients were excluded if initially treated for standard-risk medulloblastoma and subsequently treated with these protocols due to upstaging or disease progression. Results: 58 patients were identified: 26 treated as per SJMB03, 32 as per COG-99701. 5-year OS was 83 % (95 % CI 73-94 %) and 5-year PFS was 65 % (53-80 %). For patients treated as per SJMB03, 5-year OS and PFS were 80 % (65-97 %) and 75 % (60-95 %) respectively; for patients treated as per COG-99701, 5-year OS and PFS were 85 % (73-100 %) and 60 % (43-83 %). There was no significant difference in outcomes between protocols. There was a higher incidence of grade 3/4 ototoxicity (44 % vs 6 %, p = 0.001) and admission to paediatric intensive care (19 % vs 0 %, p = 0.014) in patients treated as per SJMB03 compared to COG-99701. Conclusion: These real-world outcomes are consistent with the published literature on HR-MB patients treated with these protocols within clinical trials, and provide important evidence to inform their use in routine practice.

Abstract Background Brain tumours are associated with high morbidity both from the tumour and the medical and surgical interventions used to treat them. Currently, there’s no consistent way to track and report these complications, hindering research and comparisons between treatments. One solution is to develop a core adverse outcome set to stipulate the minimum post operative complications that should be reported. The COMBAT (Core Post Operative Morbidity Set for Paediatric Brain Tumours) Project will create a core outcome set of the most important post-operative adverse outcomes for children with brain tumours, harmonising measurement and reporting of these in clinical services and research. Methods and Analysis National and international stakeholders including patients, their carers, healthcare professionals and researchers will be invited to participate. A systematic review has identified adverse outcomes reported in literature. Qualitative interviews with patients and carers are underway to identify outcomes of importance to them. A consensus process of a two round Delphi survey created from the adverse outcomes identified from the systematic review and interviews will be carried out, with a consensus meeting held to finalise the COS. The final COS will be published and disseminated to encourage uptake. We are inviting healthcare professionals and researchers with experience in paediatric neuro-oncology to participate in the consensus process. We need your expert opinion on the most important complications to include in the final core outcome set. Discussion Establishing a common language will help us better understand and address the complications of brain tumour surgery in children. This core outcome set will enable more meaningful comparisons between different treatments, help us identify areas for improvement in the care of children with brain tumours and drive future research efforts.