Characterisation of paediatric brain tumours by their MRS metabolite profiles

1H-magnetic resonance spectroscopy (MRS) has the potential to improve the noninvasive diagnostic accuracy for paediatric brain tumours. However, studies analysing large, comprehensive, multicentre datasets are lacking, hindering translation to widespread clinical practice. Single-voxel MRS (point-resolved single-voxel spectroscopy sequence, 1.5 T: echo time [TE] 23-37 ms/135-144 ms, repetition time [TR] 1500 ms; 3 T: TE 37-41 ms/135-144 ms, TR 2000 ms) was performed from 2003 to 2012 during routine magnetic resonance imaging for a suspected brain tumour on 340 children from five hospitals with 464 spectra being available for analysis and 281 meeting quality control. Mean spectra were generated for 13 tumour types. Mann-Whitney U-tests and Kruskal-Wallis tests were used to compare mean metabolite concentrations. Receiver operator characteristic curves were used to determine the potential for individual metabolites to discriminate between specific tumour types. Principal component analysis followed by linear discriminant analysis was used to construct a classifier to discriminate the three main central nervous system tumour types in paediatrics. Mean concentrations of metabolites were shown to differ significantly between tumour types. Large variability existed across each tumour type, but individual metabolites were able to aid discrimination between some tumour types of importance. Complete metabolite profiles were found to be strongly characteristic of tumour type and, when combined with the machine learning methods, demonstrated a diagnostic accuracy of 93% for distinguishing between the three main tumour groups (medulloblastoma, pilocytic astrocytoma and ependymoma). The accuracy of this approach was similar even when data of marginal quality were included, greatly reducing the proportion of MRS excluded for poor quality. Children's brain tumours are strongly characterised by MRS metabolite profiles readily acquired during routine clinical practice, and this information can be used to support noninvasive diagnosis. This study provides both key evidence and an important resource for the future use of MRS in the diagnosis of children's brain tumours.

Proceedings of the first global meeting of the Posterior Fossa Society: state of the art in cerebellar mutism syndrome

PURPOSE

The Posterior Fossa Society, an international multidisciplinary group, hosted its first global meeting designed to share the current state of the evidence across the multidisciplinary elements of pediatric post-operative cerebellar mutism syndrome (pCMS). The agenda included keynote talks from world-leading speakers, compelling abstract presentations and engaging discussions led by members of the PFS special interest groups.

METHODS

This paper is a synopsis of the first global meeting, a 3-day program held in Liverpool, England, UK, in September 2022.

RESULTS

Topics included nosology, patient and family experience, cerebellar modulation of cognition, and cerebellar cognitive affective syndrome. In addition, updates from large-scale studies were shared as well as abstracts across neuroradiology, neurosurgery, diagnosis/scoring, ataxia, and rehabilitation.

CONCLUSIONS

Based on data-driven evidence and discussions, each special interest group created research priorities to target before the second global meeting, in the spring of 2024.

Medulloblastoma in a child with osteoma cutis - a rare association due to loss of GNAS expression

OBJECTIVES

Inactivating GNAS mutations result in varied phenotypes depending on parental origin. Maternally inherited mutations typically lead to hormone resistance and Albright's hereditary osteodystrophy (AHO), characterised by short stature, round facies, brachydactyly and subcutaneous ossifications. Paternal inheritance presents with features of AHO or ectopic ossification without hormone resistance. This report describes the case of a child with osteoma cutis and medulloblastoma. The objective of this report is to highlight the emerging association between inactivating germline GNAS mutations and medulloblastoma, aiming to shed light on its implications for tumor biology and promote future development of targeted surveillance strategies to improve outcomes in paediatric patients with these mutations.

CASE PRESENTATION

A 12-month-old boy presented with multiple plaque-like skin lesions. Biopsy confirmed osteoma cutis, prompting genetic testing which confirmed a heterozygous inactivating GNAS mutation. At 2.5 years of age, he developed neurological symptoms and was diagnosed with a desmoplastic nodular medulloblastoma, SHH molecular group, confirmed by MRI and histology. Further analysis indicated a biallelic loss of GNAS in the tumor.

CONCLUSION

This case provides important insights into the role of GNAS as a tumor suppressor and the emerging association between inactivating GNAS variants and the development of medulloblastoma. The case underscores the importance of careful neurological assessment and ongoing vigilance in children with known inactivating GNAS variants or associated phenotypes. Further work to establish genotype-phenotype correlations is needed to inform optimal management of these patients.

Noise suppression of proton magnetic resonance spectroscopy improves paediatric brain tumour classification

Proton magnetic resonance spectroscopy (1 H-MRS) is increasingly used for clinical brain tumour diagnosis, but suffers from limited spectral quality. This retrospective and comparative study aims at improving paediatric brain tumour classification by performing noise suppression on clinical 1 H-MRS. Eighty-three/forty-two children with either an ependymoma (ages 4.6± $$ \pm $$ 5.3/9.3± $$ \pm $$ 5.4), a medulloblastoma (ages 6.9± $$ \pm $$ 3.5/6.5± $$ \pm $$ 4.4), or a pilocytic astrocytoma (8.0± $$ \pm $$ 3.6/6.3± $$ \pm $$ 5.0), recruited from four centres across England, were scanned with 1.5T/3T short-echo-time point-resolved spectroscopy. The acquired raw 1 H-MRS was quantified by using Totally Automatic Robust Quantitation in NMR (TARQUIN), assessed by experienced spectroscopists, and processed with adaptive wavelet noise suppression (AWNS). Metabolite concentrations were extracted as features, selected based on multiclass receiver operating characteristics, and finally used for identifying brain tumour types with supervised machine learning. The minority class was oversampled through the synthetic minority oversampling technique for comparison purposes. Post-noise-suppression 1 H-MRS showed significantly elevated signal-to-noise ratios (P < .05, Wilcoxon signed-rank test), stable full width at half-maximum (P > .05, Wilcoxon signed-rank test), and significantly higher classification accuracy (P < .05, Wilcoxon signed-rank test). Specifically, the cross-validated overall and balanced classification accuracies can be improved from 81% to 88% overall and 76% to 86% balanced for the 1.5T cohort, whilst for the 3T cohort they can be improved from 62% to 76% overall and 46% to 56%, by applying Naïve Bayes on the oversampled 1 H-MRS. The study shows that fitting-based signal-to-noise ratios of clinical 1 H-MRS can be significantly improved by using AWNS with insignificantly altered line width, and the post-noise-suppression 1 H-MRS may have better diagnostic performance for paediatric brain tumours.

Long-term cisplatin nephrotoxicity after childhood cancer: a systematic review and meta-analysis

BACKGROUND

Cisplatin is a chemotherapeutic drug commonly used in the treatment of many childhood solid malignancies. It is known to cause long-term nephrotoxicity, most commonly manifesting as reduced glomerular filtration rate and hypomagnesaemia. Existing literature regarding the epidemiology of long-term nephrotoxicity in childhood cancer describes large variation in prevalence and risk factors.

OBJECTIVES

This study is to evaluate the prevalence of, and risk factors for, long-term cisplatin nephrotoxicity after treatment for childhood cancer.

STUDY ELIGIBILITY CRITERIA

Studies were eligible for inclusion if they: (i) evaluated participants treated with cisplatin who were diagnosed with cancer < 18 years of age; (ii) investigated any author-defined measure of nephrotoxicity; and (iii) performed this evaluation 3 or more months after cisplatin cessation. Studies whose scope was broader than this were included if appropriate subgroup analysis was performed.

RESULTS

Prevalence of reduced glomerular filtration rate (GFR) ranged between 5.9 and 48.1%. Pooled prevalence of reduced GFR using studies with a modern consensus threshold of 90 ml/min/1.73 m2 was 29% (95% CI 0.0-58%). Prevalence of hypomagnesaemia ranged between 8.0 and 71.4%. Pooled prevalence of hypomagnesaemia was 37% (95% CI 22-51%). Substantial heterogeneity was present, with I2 statistics of 94% and 73% for reduced GFR and hypomagnesaemia respectively. All large, long-term follow-up studies described increased risk of reduced GFR with increasing cumulative cisplatin dose. Included studies varied as to whether cisplatin was a risk factor for proteinuria, and whether age was a risk factor for cisplatin nephrotoxicity.

LIMITATIONS

A wide range of study methodologies were noted which impeded analysis. No studies yielded data from developing health-care settings. No non-English studies were included, further limiting generalisability.

CONCLUSIONS

Both of the most common manifestations of long-term cisplatin nephrotoxicity have a prevalence of approximately a third, with increasing cumulative dose conferring increased risk of nephrotoxicity. Further work is needed to characterise the relationship between reduced GFR and hypomagnesaemia, investigate other risk factors and understand the interindividual variation in susceptibility to nephrotoxicity.

The effectiveness and safety of proton beam radiation therapy in children and young adults with Central Nervous System (CNS) tumours: a systematic review

BACKGROUND

Central nervous system (CNS) tumours account for around 25% of childhood neoplasms. With multi-modal therapy, 5-year survival is at around 75% in the UK. Conventional photon radiotherapy has made significant contributions to survival, but can be associated with long-term side effects. Proton beam radiotherapy (PBT) reduces the volume of irradiated tissue outside the tumour target volume which may potentially reduce toxicity. Our aim was to assess the effectiveness and safety of PBT and make recommendations for future research for this evolving treatment.

METHODS

A systematic review assessing the effects of PBT for treating CNS tumours in children/young adults was undertaken using methods recommended by Cochrane and reported using PRISMA guidelines. Any study design was included where clinical and toxicity outcomes were reported. Searches were to May 2021, with a narrative synthesis employed.

RESULTS

Thirty-one case series studies involving 1731 patients from 10 PBT centres were included. Eleven studies involved children with medulloblastoma / primitive neuroectodermal tumours (n = 712), five ependymoma (n = 398), four atypical teratoid/rhabdoid tumour (n = 72), six craniopharyngioma (n = 272), three low-grade gliomas (n = 233), one germ cell tumours (n = 22) and one pineoblastoma (n = 22). Clinical outcomes were the most frequently reported with overall survival values ranging from 100 to 28% depending on the tumour type. Endocrine outcomes were the most frequently reported toxicity outcomes with quality of life the least reported.

CONCLUSIONS

This review highlights areas of uncertainty in this research area. A well-defined, well-funded research agenda is needed to best maximise the potential of PBT.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO-CRD42016036802.

Metabolite profiles of medulloblastoma for rapid and non-invasive detection of molecular disease groups

BACKGROUND

The malignant childhood brain tumour, medulloblastoma, is classified clinically into molecular groups which guide therapy. DNA-methylation profiling is the current classification 'gold-standard', typically delivered 3-4 weeks post-surgery. Pre-surgery non-invasive diagnostics thus offer significant potential to improve early diagnosis and clinical management. Here, we determine tumour metabolite profiles of the four medulloblastoma groups, assess their diagnostic utility using tumour tissue and potential for non-invasive diagnosis using in vivo magnetic resonance spectroscopy (MRS).

METHODS

Metabolite profiles were acquired by high-resolution magic-angle spinning NMR spectroscopy (MAS) from 86 medulloblastomas (from 59 male and 27 female patients), previously classified by DNA-methylation array (WNT (n = 9), SHH (n = 22), Group3 (n = 21), Group4 (n = 34)); RNA-seq data was available for sixty. Unsupervised class-discovery was performed and a support vector machine (SVM) constructed to assess diagnostic performance. The SVM classifier was adapted to use only metabolites (n = 10) routinely quantified from in vivo MRS data, and re-tested. Glutamate was assessed as a predictor of overall survival.

FINDINGS

Group-specific metabolite profiles were identified; tumours clustered with good concordance to their reference molecular group (93%). GABA was only detected in WNT, taurine was low in SHH and lipids were high in Group3. The tissue-based metabolite SVM classifier had a cross-validated accuracy of 89% (100% for WNT) and, adapted to use metabolites routinely quantified in vivo, gave a combined classification accuracy of 90% for SHH, Group3 and Group4. Glutamate predicted survival after incorporating known risk-factors (HR = 3.39, 95% CI 1.4-8.1, p = 0.025).

INTERPRETATION

Tissue metabolite profiles characterise medulloblastoma molecular groups. Their combination with machine learning can aid rapid diagnosis from tissue and potentially in vivo. Specific metabolites provide important information; GABA identifying WNT and glutamate conferring poor prognosis.

FUNDING

Children with Cancer UK, Cancer Research UK, Children's Cancer North and a Newcastle University PhD studentship.

Preoperative word-finding difficulties in children with posterior fossa tumours: a European cross-sectional study

PURPOSE

Posterior fossa tumour surgery in children entails a high risk for severe speech and language impairments, but few studies have investigated the effect of the tumour on language prior to surgery. The current crosslinguistic study addresses this gap. We investigated the prevalence of preoperative word-finding difficulties, examined associations with medical and demographic characteristics, and analysed lexical errors.

METHODS

We included 148 children aged 5-17 years with a posterior fossa tumour. Word-finding ability was assessed by means of a picture-naming test, Wordrace, and difficulties in accuracy and speed were identified by cut-off values. A norm-based subanalysis evaluated performance in a Swedish subsample. We compared the demographic and medical characteristics of children with slow, inaccurate, or combined slow and inaccurate word finding to the characteristics of children without word-finding difficulties and conducted a lexical error analysis.

RESULTS

Thirty-seven percent (n = 55) presented with slow word finding, 24% (n = 35) with inaccurate word finding, and 16% (n = 23) with both slow and inaccurate word finding. Children with posterior fossa tumours were twice as slow as children in the norming sample. Right-hemisphere and brainstem location posed a higher risk for preoperative word-finding difficulties, relative to left-hemisphere location, and difficulties were more prevalent in boys than in girls. The most frequent errors were lack of response and semantically related sideordinated words.

CONCLUSION

Word-finding difficulties are frequent in children with posterior fossa tumours, especially in boys and in children with right-hemisphere and brainstem tumours. Errors resemble those observed in typical development and children with word-finding difficulties.

Can I go home now? The safety and efficacy of a new UK paediatric febrile neutropenia protocol for risk-stratified early discharge on oral antibiotics

OBJECTIVE

To evaluate a new protocol of risk stratification and early discharge for children with febrile neutropenia (FN).

DESIGN

Prospective service evaluation from 17 April 2020 to 16 April 2021.

SETTING

13 specialist centres in the UK.

PATIENTS

405 children presenting with FN.

INTERVENTION

All children received intravenous antibiotics at presentation. Risk stratification was determined using the Australian-UK-Swiss (AUS) rule and eligibility for homecare assessed using criteria including disease, chemotherapy, presenting features and social factors. Those eligible for homecare could be discharged on oral antibiotics after a period of observation proportional to their risk group.

MAIN OUTCOME MEASURES

Median duration of admission and of intravenous antibiotics, and percentage of patients with positive blood cultures, significant infection, readmission within 7 days of initial presentation, intensive care unit (ICU) admission, death from infection and death from other causes.

RESULTS

13 centres contributed 729 initial presentations of 405 patients. AUS rule scores were positively correlated with positive blood cultures, significant infection, ICU admission and death. 20% of children were eligible for homecare with oral antibiotics, of which 55% were low risk (AUS 0-1). 46% low-risk homecare eligible patients were discharged by 24 hours vs 2% homecare ineligible. Homecare readmission rates were 14% overall and 16% for low-risk cases (similar to a meta-analysis of previous studies). No child eligible for homecare was admitted to ICU or died.

CONCLUSIONS

Use of the AUS rule and homecare criteria allow for safe early outpatient management of children with FN.

Prevalence of dysphagia following posterior fossa tumour resection in children: the Alder Hey experience

BACKGROUND

Surgery for posterior fossa tumours (PFTs) in children is associated with bulbar palsy and swallowing difficulties although this risk is not well defined in the literature and issues contributing to dysphagia following surgery are not fully understood.

AIMS

This study aims to study the eating, drinking and swallowing function of children following PFT resection in a specialist paediatric neurosurgery centre. This included the frequency and duration of dysphagia, the risk of aspiration and the link between tumour type and dysphagia.

MATERIALS AND METHODS

This is a retrospective review of children undergoing surgery for PFT between 2014 and 2019. Information was obtained from the patients' hospital and speech and language therapy (SLT) notes, oncology database and clinical letters. The International Dysphagia Diet Standardisation Initiative (IDDSI) Framework was used to describe food and fluid modifications.

RESULTS

Seventy children had surgery to resect a posterior fossa tumour at Alder Hey from 2014 to 2019. Thirty-one children were included in the study following referral to SLT. Videofluoroscopy (VF) was undertaken at our institution in 68% (21/31) of cases. Fifty-two percent (11/21) of children aspirated or were considered at risk, and 55% (6/11) of those who aspirated showed silent aspiration. After 3 months, 43% (13/30) still required modified food and/or fluid textures, with this proportion reducing as time progressed. By tumour type, VF was performed in 5/7 medulloblastoma patients with 3/5 showing aspiration and 3/3 silently aspirating; in 8/9 patients with ependymoma with 4/8 patients aspirating with 2/4 showing silent aspiration; and 6/12 glioma patients with 4/6 aspirating with 1/4 showing silent aspiration.

CONCLUSION

Swallowing difficulties, including silent aspiration, are an important complication of PFT resection. A proportion of children will need ongoing food and/or fluid modification. Further study into dysphagia following PFT resection is indicated.

Applying machine learning classifiers to automate quality assessment of paediatric dynamic susceptibility contrast (DSC-) MRI data

OBJECTIVE

Investigate the performance of qualitative review (QR) for assessing dynamic susceptibility contrast (DSC-) MRI data quality in paediatric normal brain and develop an automated alternative to QR.

METHODS

1027 signal-time courses were assessed by Reviewer 1 using QR. 243 were additionally assessed by Reviewer 2 and % disagreements and Cohen's κ (κ) were calculated. The signal drop-to-noise ratio (SDNR), root mean square error (RMSE), full width half maximum (FWHM) and percentage signal recovery (PSR) were calculated for the 1027 signal-time courses. Data quality thresholds for each measure were determined using QR results. The measures and QR results trained machine learning classifiers. Sensitivity, specificity, precision, classification error and area under the curve from a receiver operating characteristic curve were calculated for each threshold and classifier.

RESULTS

Comparing reviewers gave 7% disagreements and κ = 0.83. Data quality thresholds of: 7.6 for SDNR; 0.019 for RMSE; 3 s and 19 s for FWHM; and 42.9 and 130.4% for PSR were produced. SDNR gave the best sensitivity, specificity, precision, classification error and area under the curve values of 0.86, 0.86, 0.93, 14.2% and 0.83. Random forest was the best machine learning classifier, giving sensitivity, specificity, precision, classification error and area under the curve of 0.94, 0.83, 0.93, 9.3% and 0.89.

CONCLUSION

The reviewers showed good agreement. Machine learning classifiers trained on signal-time course measures and QR can assess quality. Combining multiple measures reduces misclassification.

ADVANCES IN KNOWLEDGE

A new automated quality control method was developed, which trained machine learning classifiers using QR results.

Genome-wide analyses of platinum-induced ototoxicity in childhood cancer patients: Results of GO-CAT and United Kingdom MAGIC consortia

Hearing loss (ototoxicity) is a major adverse effect of cisplatin and carboplatin chemotherapy. The aim of this study is to identify novel genetic variants that play a role in platinum-induced ototoxicity. Therefore, a genome-wide association study was performed in the Genetics of Childhood Cancer Treatment (GO-CAT) cohort (n = 261) and the United Kingdom Molecular Genetics of Adverse Drug Reactions in Children Study (United Kingdom MAGIC) cohort (n = 248). Results of both cohorts were combined in a meta-analysis. In primary analysis, patients with SIOP Boston Ototoxicity Scale grade ≥1 were considered cases, and patients with grade 0 were controls. Variants with a p-value <10^-5 were replicated in previously published data by the PanCareLIFE cohort (n = 390). No genome-wide significant associations were found, but variants in TSPAN5, RBBP4P5, AC010090.1 and RNU6-38P were suggestively associated with platinum-induced ototoxicity. The lowest p-value was found for rs7671702 in TSPAN5 (odds ratio 2.0 (95% confidence interval 1.5-2.7), p-value 5.0 × 10^-7). None of the associations were significant in the replication cohort, although the effect directions were consistent among all cohorts. Validation and functional understanding of these genetic variants could lead to more insights in the development of platinum-induced ototoxicity.

Rare embryonal and sarcomatous central nervous system tumours: State-of-the art and future directions

The introduction of molecular methods into the diagnostics of central nervous system (CNS) tumours and the subsequent deciphering of their molecular heterogeneity has resulted in a significant impact on paediatric neurooncology. Particularly in the field of rare embryonal and sarcomatous CNS tumours, novel tumour types have been delineated and introduced in the recent 5th edition of the WHO classification of CNS tumours. The rarity and novelty of these tumour types result in diagnostic and therapeutic challenges. Apart from distinct histopathological and molecular features, these tumour types exhibit characteristic clinical properties and require different therapeutic approaches for optimal patient management. However, based on the limited availability of clinical data, current therapeutic recommendations have to be based on data from small, predominantly retrospective patient cohorts. Within this article, we provide guidance for diagnostic work-up and clinical management of rare CNS embryonal tumours ('embryonal tumour with multi-layered rosettes', ETMR; 'CNS neuroblastoma, FOXR2-activated', CNS NB-FOXR2; 'CNS tumour with BCOR-ITD, CNS BCOR-ITD) and rare CNS sarcomatous tumours ('primary intracranial sarcoma, DICER1-mutant', CNS DICER1; 'CIC-rearranged sarcoma', CNS CIC). By emphasizing the significant consequences on patient management in paediatric CNS tumours, we want to encourage wide implementation of comprehensive molecular diagnostics and stress the importance for joint international efforts to further collect and study these rare tumour types.

Long term quality of life outcomes following surgical resection alone for benign paediatric intracranial tumours

PURPOSE

Survivors of paediatric intracranial tumours are at increased risk of psychosocial, neuro-developmental, and functional impairment. This study aimed to evaluate long-term health-related quality-of-life (HRQOL) outcomes in patients with benign paediatric brain tumours treated curatively with surgical resection alone.

METHODOLOGY

This was a cross-sectional study of patients with benign paediatric intracranial tumours managed with surgery alone between 2000 and 2015. Eligible patients with a minimum of 5-years follow-up after surgery were identified. Validated health-related quality of life (HRQOL) questionnaires were administered: SF-36, QLQ-BN20, QLQ-C30 and PedsQL™.

RESULTS

Twenty-three patients participated (median age at surgery 13 years; range 1-18; 12 male). The most common diagnosis was pilocytic astrocytoma (n = 15). Median time from surgery to participation was 11 years(range 6-19). Fourteen patients achieved A-level qualifications and two obtained an undergraduate degree. Twelve patients were employed, eight were studying and three were unemployed or volunteering. HRQOL outcomes demonstrated significant limitation from social functioning (p = 0.03) and cognitive functioning (p = 0.023) compared to the general population. Patients also experienced higher rates of loss of appetite (p = 0.009) and nausea and vomiting (p = 0.031). Ten patients were under transitional teenager and young-adult (TYA) clinic follow-up. TYA patients achieved higher levels of education (p = 0.014), were more likely to hold a driver's license (p = 0.041) compared to patients not followed-up through these services.

CONCLUSIONS

Childhood brain-tumour survivors have a greater risk of developing psychological, neuro-cognitive and physical impairment. Early comprehensive assessment, specialist healthcare and TYA services are vital to support these patients.

A Nationwide Evaluation of Bevacizumab-based Treatments in Paediatric Low-Grade Glioma in the UK: Safety. Efficacy, Visual Morbidity and Outcomes

BACKGROUND

Bevacizumab is increasingly used in children with Paediatric Low-Grade Glioma (PLGG) despite limited evidence. A nationwide UK service evaluation was conducted to provide larger cohort 'real life' safety and efficacy data including functional visual outcomes.

METHODS

Children receiving Bevacizumab-based treatments (BBT) for PLGG (2009-2020) from 11 centres were included. Standardised neuro-radiological (RANO-LGG) and visual (logMAR visual acuity) criteria were used to assess clinical-radiological correlation, survival outcomes and multivariate prognostic analysis.

RESULTS

Eighty-eight children with PLGG received BBT either as 3 rd line with Irinotecan (85%) or alongside 1 st/2 nd line chemotherapies (15%). Toxicity was limited and minimal. Partial response (PR, 40%), stable disease (SD, 49%), and progressive disease (PD, 11%) were seen during BBT. However, 65% progressed at 8 months (median) from BBT cessation, leading to a radiology-based 3yr-progression-free survival (PFS) of 29%. Diencephalic syndrome (p= 0.03) was associated with adverse PFS. Pre-existing visual morbidity included unilateral (25%) or bilateral (11%) blindness. Improvement (29%) or stabilisation (49%) of visual acuity were achieved, more often in patients' best eyes. Vision deteriorated during BBT in 14 (22%), with 3-year visual-PFS of 53%; more often in patients' worst eyes. A superior visual outcome (p=0.023) was seen in Neurofibromatosis type 1-associated Optic Pathway Glioma (OPG). Concordance between visual and radiological responses was 36%; optimised to 48% using only best eye responses.

CONCLUSIONS

BBTs provide effective short-term PLGG control and delay further progression, with a better sustained visual (best >worst eye) than radiological response. Further research could optimise the role of BBTs towards a potentially sight-saving strategy in OPG.

Long Term Quality of Life Outcomes Following Surgical Resection Alone for Benign Paediatric Intracranial Tumours

AIMS

Survivors of paediatric intracranial malignancies are at increased risk of psychosocial, neuro-developmental and functional impairment, important measures of patients’ well-being. This study aimed to evaluate long-term quality of life outcomes (QOL) in patients with benign paediatric brain tumours treated curatively with surgical resection alone.

METHOD

Cross-sectional cohort study of benign paediatric intracranial tumours managed with surgery alone between 2000-2015. Validated QOL questionnaires were administered: SF-36, QLQ-BN20, QLQ-C30 and PedsQLTM.

RESULTS

Twenty-three patients participated (median age at surgery 13 years; range 1-18), twelve were male. The most common diagnosis was pilocytic astrocytoma (n=15). Median time from surgery to participation was 11 years (range 6-19). Fourteen patients achieved A-level qualifications and two obtained an undergraduate degree. Twelve patients were employed, eight were studying and three were unemployed or volunteering. Twelve patients were currently driving. QOL outcomes demonstrated significant limitation from social functioning (p=0.03) and cognitive functioning (p=0.023) compared to the general population norms. Patients also experienced increased loss of appetite (p=0.009) and symptoms of nausea and vomiting (p=0.031). Ten patients were under transitional teenager and young-adult (TYA) clinic follow-up. TYA patients achieved higher levels of education (p=0.014), were more likely to hold a driver’s license (p=0.041) and had improved physical functioning (p=0.005) compared to patients not transitioned through these services.

CONCLUSION

Childhood brain-tumour survivors are particularly vulnerable and at greater risk of developing psychological, neuro-cognitive, socialisation and physical development challenges. Early identification, comprehensive assessment and specialist TYA cancer healthcare input are vital to support these patients and improve their quality of life.

Medulloblastoma group 3 and 4 tumors comprise a clinically and biologically significant expression continuum reflecting human cerebellar development

Medulloblastoma is currently subclassified into distinct DNA methylation subgroups/subtypes with particular clinico-molecular features. Using RNA sequencing (RNA-seq) in large, well-annotated cohorts of medulloblastoma, we show that transcriptionally group 3 and group 4 medulloblastomas exist as intermediates on a bipolar continuum between archetypal group 3 and group 4 entities. Continuum position is prognostic, reflecting a propensity for specific DNA copy-number changes, and specific switches in isoform/enhancer usage and RNA editing. Examining single-cell RNA-seq (scRNA-seq) profiles, we show that intratumoral transcriptional heterogeneity along the continuum is limited in a subtype-dependent manner. By integrating with a human scRNA-seq reference atlas, we show that this continuum is mirrored by an equivalent continuum of transcriptional cell types in early fetal cerebellar development. We identify distinct developmental niches for all four major subgroups and link each to a common developmental antecedent. Our findings show a transcriptional continuum arising from oncogenic disruption of highly specific fetal cerebellar cell types, linked to almost every aspect of group 3/group 4 molecular biology and clinico-pathology.

Left-handedness should not be overrated as a risk factor for postoperative speech impairment in children after posterior fossa tumour surgery: a prospective European multicentre study

PURPOSE

Cerebellar mutism syndrome (CMS) is a severe neurological complication of posterior fossa tumour surgery in children, and postoperative speech impairment (POSI) is the main component. Left-handedness was previously suggested as a strong risk factor for POSI. The aim of this study was to investigate the relationship between handedness and the risk of POSI.

METHODS

We prospectively included children (aged < 18 years) undergoing surgery for posterior fossa tumours in 26 European centres. Handedness was assessed pre-operatively and postoperative speech status was categorised as either POSI (mutism or reduced speech) or habitual speech, based on the postoperative clinical assessment. Logistic regression was used in the risk factor analysis of POSI as a dichotomous outcome.

RESULTS

Of the 500 children included, 37 (7%) were excluded from the present analysis due to enrolment at a reoperation; another 213 (43%) due to missing data about surgery (n = 37) and/or handedness (n = 146) and/or postoperative speech status (n = 53). Out of the remaining 250 (50%) patients, 20 (8%) were left-handed and 230 (92%) were right-handed. POSI was observed equally frequently regardless of handedness (5/20 [25%] in left-handed, 61/230 [27%] in right-handed, OR: 1.08 [95% CI: 0.40-3.44], p = 0.882), also when adjusted for tumour histology, location and age.

CONCLUSION

We found no difference in the risk of POSI associated with handedness. Our data do not support the hypothesis that handedness should be of clinical relevance in the risk assessment of CMS.

LGG-09. A Nationwide Service Evaluation of Safety, Radiologic and Visual Outcome Refining Bevacizumab-based Treatments in Children with Progressive Low-Grade Glioma

INTRODUCTION: Bevacizumab/Irinotecan is currently 3rd-line treatment in the UK for progressive Paediatric Low-Grade Glioma (PLGG) based on limited evidence. A nationwide service evaluation was conducted to review its safety and efficacy amongst a larger cohort.

METHODS: Data from children with PLGG receiving Bevacizumab-based Treatments (BBT) from 11 UK Centres (2009-2020) were reviewed. Radiological and visual outcomes were based on standardized measurements. Clinical-radiological correlation was investigated. Time to progression from BBT stop, progression free-survival (PFS) curves and multivariate analysis of prognostic factors (p 0.05) were performed.

RESULTS: 88 children with PLGG (88% OPG, 24% NF1) had BBT for radiological (43%), visual (20%) or combined (27%) progression, after 40 months (median) from diagnosis. Amongst OPG cases, visual acuity (VA) per eye (better/worse) before BBT was logMAR 0.0-0.3 (23/7) 0.3 - 1.0 (27/20), &gt; 1.0 (14/18) and LP/NLP (8/27), with 19/8 children respectively blind (LP/NLP) in one or both eyes. Bevacizumab 10 mg/kg every 14 days (median 24 doses) was given as 3rd line+ with Irinotecan (85%) or alongside 1st/2nd line chemo (15%) leading to remarkable radiological (88%) and visual (74%) responses (stable or improved) within 3-6 months, with limited toxicity. 12% progressed on treatment, and 8% died unrelated to BBT. After initial response 65% progressed at a median of 8 months (4 - 23) after BBT, resulting in 3-year-all-causes-PFS of 16% and 3-yr-visual-PFS of 45% from start of BBT. Visual concordance with MRI was poor (36%) but increases (47%) when better-eye determines visual outcome. Lack of NF1 and diencephalic syndrome (DS) at presentation were independent negative prognostic factors for PFS.

CONCLUSIONS: A remarkable but transient effect of BBT has been confirmed. Visual &gt; radiological responses can be sustained after BBT. Variations in current BBT strategies justifies further research, including the potential upfront use alongside conventional first-line chemotherapy as sight-saving strategy.

SURG-13. The COMBAT Project - Core post operative morbidity set for paediatric brain tumours

BACKGROUND: Brain tumours are associated with high morbidity both from the tumour and the medical and surgical interventions used to treat them. Post operative morbidity reporting following surgery for paediatric brain tumours is poor due to the lack of a common language when reporting harms. One solution is to develop a core adverse outcome set to stipulate the minimum post operative harms that should be reported. The COMBAT (Core post operative morbidity set for paediatric brain tumours) Project will develop a core adverse outcome set that can be applied to post operative paediatric brain tumour patients to harmonise how harms are measured and reported, enabling comparison between different trials, studies and clinical services. We aim to generate interest in the COMBAT Project and invite collaboration with healthcare professionals and researchers experienced in paediatric neuro oncology surgery. METHODS AND ANALYSIS : A systematic review will identify harms reported in post operative paediatric brain tumour patients and how they are measured. We will engage with national and international stakeholders including healthcare professionals, researchers, patients and their carers. Qualitative interviews with patients and carers will identify any important harms not extracted in the systematic review. A Delphi survey will be created from the harms identified. An international consensus meeting will be held to finalise the core adverse outcomes set. The final core adverse outcome set will be published and disseminated to encourage uptake. DISCUSSION: There is a clear need for a common language to harmonise measurement and reporting of harms following surgery for paediatric brain tumour patients. The core adverse outcome set will be developed with collaboration with key stakeholder groups to ensure it is representative. It will be used to standardise surgical morbidity outcome measurement and reporting in trials, studies and clinical practice and will inform future research in this field.

Metabolite selection for machine learning in childhood brain tumour classification

MRS can provide high accuracy in the diagnosis of childhood brain tumours when combined with machine learning. A feature selection method such as principal component analysis is commonly used to reduce the dimensionality of metabolite profiles prior to classification. However, an alternative approach of identifying the optimal set of metabolites has not been fully evaluated, possibly due to the challenges of defining this for a multi-class problem. This study aims to investigate metabolite selection from in vivo MRS for childhood brain tumour classification. Multi-site 1.5 T and 3 T cohorts of patients with a brain tumour and histological diagnosis of ependymoma, medulloblastoma and pilocytic astrocytoma were retrospectively evaluated. Dimensionality reduction was undertaken by selecting metabolite concentrations through multi-class receiver operating characteristics and compared with principal component analysis. Classification accuracy was determined through leave-one-out and k-fold cross-validation. Metabolites identified as crucial in tumour classification include myo-inositol (P < 0.05, AUC = 0 . 81 ± 0 . 01 ), total lipids and macromolecules at 0.9 ppm (P < 0.05, AUC = 0 . 78 ± 0 . 01 ) and total creatine (P < 0.05, AUC = 0 . 77 ± 0 . 01 ) for the 1.5 T cohort, and glycine (P < 0.05, AUC = 0 . 79 ± 0 . 01 ), total N-acetylaspartate (P < 0.05, AUC = 0 . 79 ± 0 . 01 ) and total choline (P < 0.05, AUC = 0 . 75 ± 0 . 01 ) for the 3 T cohort. Compared with the principal components, the selected metabolites were able to provide significantly improved discrimination between the tumours through most classifiers (P < 0.05). The highest balanced classification accuracy determined through leave-one-out cross-validation was 85% for 1.5 T 1 H-MRS through support vector machine and 75% for 3 T 1 H-MRS through linear discriminant analysis after oversampling the minority. The study suggests that a group of crucial metabolites helps to achieve better discrimination between childhood brain tumours.

Dynamic susceptibility-contrast magnetic resonance imaging with contrast agent leakage correction aids in predicting grade in pediatric brain tumours: a multicenter study

BACKGROUND

Relative cerebral blood volume (rCBV) measured using dynamic susceptibility-contrast MRI can differentiate between low- and high-grade pediatric brain tumors. Multicenter studies are required for translation into clinical practice.

OBJECTIVE

We compared leakage-corrected dynamic susceptibility-contrast MRI perfusion parameters acquired at multiple centers in low- and high-grade pediatric brain tumors.

MATERIALS AND METHODS

Eighty-five pediatric patients underwent pre-treatment dynamic susceptibility-contrast MRI scans at four centers. MRI protocols were variable. We analyzed data using the Boxerman leakage-correction method producing pixel-by-pixel estimates of leakage-uncorrected (rCBVuncorr) and corrected (rCBVcorr) relative cerebral blood volume, and the leakage parameter, K2. Histological diagnoses were obtained. Tumors were classified by high-grade tumor. We compared whole-tumor median perfusion parameters between low- and high-grade tumors and across tumor types.

RESULTS

Forty tumors were classified as low grade, 45 as high grade. Mean whole-tumor median rCBVuncorr was higher in high-grade tumors than low-grade tumors (mean ± standard deviation [SD] = 2.37±2.61 vs. -0.14±5.55; P<0.01). Average median rCBV increased following leakage correction (2.54±1.63 vs. 1.68±1.36; P=0.010), remaining higher in high-grade tumors than low grade-tumors. Low-grade tumors, particularly pilocytic astrocytomas, showed T1-dominant leakage effects; high-grade tumors showed T2*-dominance (mean K2=0.017±0.049 vs. 0.002±0.017). Parameters varied with tumor type but not center. Median rCBVuncorr was higher (mean = 1.49 vs. 0.49; P=0.015) and K2 lower (mean = 0.005 vs. 0.016; P=0.013) in children who received a pre-bolus of contrast agent compared to those who did not. Leakage correction removed the difference.

CONCLUSION

Dynamic susceptibility-contrast MRI acquired at multiple centers helped distinguish between children's brain tumors. Relative cerebral blood volume was significantly higher in high-grade compared to low-grade tumors and differed among common tumor types. Vessel leakage correction is required to provide accurate rCBV, particularly in low-grade enhancing tumors.

Opportunities and challenges for the development of "core outcome sets" in neuro-oncology

Core Outcome Sets (COS) define minimum outcomes to be measured and reported in clinical effectiveness trials for a particular health condition/health area. Despite recognition as critical to clinical research design for other health areas, none have been developed for neuro-oncology. COS development projects should carefully consider: scope (how the COS should be used), stakeholders involved in development (including patients as both research partners and participants), and consensus methodologies used (typically a Delphi survey and consensus meeting), as well as dissemination plans. Developing COS for neuro-oncology is potentially challenging due to extensive tumor subclassification (including molecular stratification), different symptoms related to anatomical tumor location, and variation in treatment options. Development of a COS specific to tumor subtype, in a specific location, for a particular intervention may be too narrow and would be unlikely to be used. Equally, a COS that is applicable across a wider area of neuro-oncology may be too broad and therefore lack specificity. This review describes why and how a COS may be developed, and discusses challenges for their development, specific to neuro-oncology. The COS under development are briefly described, including: adult glioma, incidental/untreated meningioma, meningioma requiring intervention, and adverse events from surgical intervention for pediatric brain tumors.

Surgical management and outcomes of paediatric ovarian tumours-a 25-year UK single centre experience

BACKGROUND

Ovarian neoplasms in children are rare heterogeneous lesions with variable biological behaviour and outcome. We herein report a 25-year experience from a UK specialist centre managing paediatric ovarian tumours.

METHODS

All female patients requiring operation for ovarian tumours were identified during the study period 1990-2018. Patient demographics, clinical presentation, and management are highlighted.

RESULTS

Eighty-eight females with 101 ovarian tumours including cases with synchronous and metachronous neoplasms were documented. Mean age at diagnosis was 11.8 years. Tumours were equally distributed in left and right ovary(s). Bilateral disease occurred in 11 (10.8%) patients. Eighty-six (85%) neoplasms were benign and 15 (15%) malignant requiring in addition to surgery chemotherapy and/or radiation. There were no significant difference(s) observed in maximum tumour diameter in benign vs malignant lesions. Only half of malignant tumours had positive tumour markers. Fifteen patients (15%) had ovarian lesions that were metastatic at primary presentation including a rare case of disseminated peritoneal gliomatosis. Surgical management included salpingo-oopherectomy n = 21 (21%), ovary excision n = 33 (33%), 'ovary sparing' tumourectomy n = 34 (34%), and cyto-reductive extirpation in 2 cases (2%). Lymphadenectomy was performed in 9 patients (9%) together with peritoneal fluid cytology in 18 cases (18%) who had abdominal ascites. Omentectomy was required in 14 patients (14%), multiple peritoneal biopsy(s)-in 11 cases (11%) and biopsy of other suspicious involved organs notably bowel, gut mesentery and contralateral ovary in 7 (7%) further patients. Recurrent and metachronous lesions occurred in 10 (10%) cases in those with teratoma (n = 9) and adenocarcinoma(s) (n = 1). Overall patient survival was 97% with only 3 deaths-mucinous cystadenocarcinoma (n = 1), desmoplastic small round cell tumour of ovarian origin (n = 1), and a small cell carcinoma of ovary with hypercalcaemia (n = 1).

CONCLUSIONS

Findings from this study show an excellent survival (97%) for paediatric ovarian neoplasms. Rare malignant neoplasms though do carry a poor prognosis. In the modern era of care, all efforts should be made to preserve future hormonal health and fertility with 'ovarian sparing' operation(s) where appropriate.

Combining multi-site magnetic resonance imaging with machine learning predicts survival in pediatric brain tumors

Brain tumors represent the highest cause of mortality in the pediatric oncological population. Diagnosis is commonly performed with magnetic resonance imaging. Survival biomarkers are challenging to identify due to the relatively low numbers of individual tumor types. 69 children with biopsy-confirmed brain tumors were recruited into this study. All participants had perfusion and diffusion weighted imaging performed at diagnosis. Imaging data were processed using conventional methods, and a Bayesian survival analysis performed. Unsupervised and supervised machine learning were performed with the survival features, to determine novel sub-groups related to survival. Sub-group analysis was undertaken to understand differences in imaging features. Survival analysis showed that a combination of diffusion and perfusion imaging were able to determine two novel sub-groups of brain tumors with different survival characteristics (p < 0.01), which were subsequently classified with high accuracy (98%) by a neural network. Analysis of high-grade tumors showed a marked difference in survival (p = 0.029) between the two clusters with high risk and low risk imaging features. This study has developed a novel model of survival for pediatric brain tumors. Tumor perfusion plays a key role in determining survival and should be considered as a high priority for future imaging protocols.

OS03.5.A Corelation between longitudinal t2 MRI radiomic primary texture feature values and radiation dose in non-tumoral regions of the brain in paediatric brain tumours

BACKGROUND

Paediatric brain tumour survivors may have treatment toxicity associated with signal change on follow-up MRI. Quantitative MRI texture features can potentially be used as surrogates of the underlying tissue changes following radiation therapy.

MATERIAL AND METHODS

Longitudinal retrospective study in 51 paediatric primary brain tumours treated with photon (N=30) and proton (N=21) radiotherapy (RT). T2 MRI scans at baseline and multiple time point from the date of surgery to 2 years following radiotherapy were selected for the textural analysis. Scans were bias corrected, registered with the CT dose maps and with baseline scan for each patient using 3Dslicer. Regions of interest (ROI) of fixed diameter were drawn in 11 predetermined non-tumoral regions of brain including in peri-tumoural region (PTV). ROIs were placed in homogenous white/grey matter. Radiation dose was calculated in each of these 11 ROIs and texture features were extracted using pyradiomics. Data were analysed using machine learning and statistical analysis. General linear multivariate model was used to corelate primary texture features over period of 24 months and radiation dose, time, effect of dose*time together at each ROI separately.

RESULTS

There were Brainstem 4, Cerebellar19, Hemispheric cerebral 7 and Supratentorial midline 10 tumours. Median age at diagnosis was 8.26 years (range: 0–20). Median RT treatment dose was 28.52Gy (0-60Gy). Multivariate analysis shows significant corelation (p &lt; 0.001) between radiation dose and longitudinal primary texture features in all 11ROIs. Time showed corelation with feature values only in 3 ROIs and dose* time showed corelation in 5ROIs. Primary (statistical) feature values showing consistent correlation with dose in all 11 ROIs over 24 months are total energy, 10%, 90%, energy, entropy, mean, median, and minimum.

CONCLUSION

Radiomic texture analysis is a promising modality to understand dose related textural changes in the normal part of brain in paediatric brain tumour patients treated with radiation therapy. Radiomic changes need to be related to neurological outcomes in future research.

Evolution of surgical attitudes to paediatric thalamic tumours: the alder hey experience

PURPOSE

Attitudes to surgery for paediatric thalamic tumours have evolved due to improved preoperative imaging modalities and the advent of intraoperative MRI (iMRI) as well as enhanced understanding of tumour biology. We review the developments in our local practice over the last three decades with particular attention to the impact of iMRI.

METHODS

We identified all paediatric patients from a prospectively maintained neuro-oncology database who received surgery for a thalamic tumour (n = 30). All children were treated in a single UK tertiary paediatric neurosurgery centre between January 1991 and June 2020. Twenty patients underwent surgical resection, the remainder (10) undergoing biopsy only. Pre-operative surgical intent (biopsy versus debulking, near-total resection, or complete resection) as well as the use of iMRI were prospectively recorded. Complications recorded in clinical documentation between postoperative days 0 and 30 were retrospectively graded using a modified version of the Clavien Dindo scale. The extent of resection with respect to the pre-determined surgical aim was also recorded. Data on patient survival and disease progression status were obtained retrospectively.

RESULTS

In our series, there were 42 procedures (25 craniotomies, 17 biopsies) performed on 30 patients (17 male, with a median age of 8 at surgery). Of the 25 surgical resections performed, complete resection was achieved in 9 (36%), near-total resection in 10 (40%), and limited debulking in 6 (24%). The predetermined surgical aim was achieved or exceeded in 91.3% of cases. The proportion of craniotomies for which substantial resection was achieved, increased from 37.5 to 94.2% with use of iMRI (p = 0.014). Surgical morbidity was not associated with greater extent of surgical resection. High-grade histology is identified as the only independent significant factor influencing overall survival as calculated by Cox proportional hazards model (p = 0.006).

CONCLUSION

We note a significant change in the rate and extent of attempted resection of paediatric thalamic tumours that has developed over the last 3 decades. Use of iMRI is associated with a significant increase in substantial tumour resection surgeries. This is not associated with any significant level of surgical morbidity. Improvements in pre- and intra-operative imaging alongside better understanding of tumour biology facilitate patient selection and a surgically more aggressive approach in selected cases whilst maintaining safety and avoiding operative morbidity.

Emergence and maintenance of actionable genetic drivers at medulloblastoma relapse

Background

Less than 5% of medulloblastoma (MB) patients survive following failure of contemporary radiation-based therapies. Understanding the molecular drivers of medulloblastoma relapse (rMB) will be essential to improve outcomes. Initial genome-wide investigations have suggested significant genetic divergence of the relapsed disease.

Methods

We undertook large-scale integrated characterization of the molecular features of rMB—molecular subgroup, novel subtypes, copy number variation (CNV), and driver gene mutation. 119 rMBs were assessed in comparison with their paired diagnostic samples (n = 107), alongside an independent reference cohort sampled at diagnosis (n = 282). rMB events were investigated for association with outcome post-relapse in clinically annotated patients (n = 54).

Results

Significant genetic evolution occurred over disease-course; 40% of putative rMB drivers emerged at relapse and differed significantly between molecular subgroups. Non-infant MBSHH displayed significantly more chromosomal CNVs at relapse (TP53 mutation-associated). Relapsed MB_Group4 demonstrated the greatest genetic divergence, enriched for targetable (eg, CDK amplifications) and novel (eg, USH2A mutations) events. Importantly, many hallmark features of MB were stable over time; novel subtypes (>90% of tumors) and established genetic drivers (eg, SHH/WNT/P53 mutations; 60% of rMB events) were maintained from diagnosis. Critically, acquired and maintained rMB events converged on targetable pathways which were significantly enriched at relapse (eg, DNA damage signaling) and specific events (eg, 3p loss) predicted survival post-relapse.

Conclusions

rMB is characterised by the emergence of novel events and pathways, in concert with selective maintenance of established genetic drivers. Together, these define the actionable genetic landscape of rMB and provide a basis for improved clinical management and development of stratified therapeutics, across disease-course.

Therapeutic implications of improved molecular diagnostics for rare CNS-embryonal tumor entities: results of an international, retrospective study

BACKGROUND

Only few data are available on treatment-associated behavior of distinct rare CNS-embryonal tumor entities previously treated as "CNS-primitive neuroectodermal tumors" (CNS-PNET). Respective data on specific entities, including CNS neuroblastoma, FOXR2 activated (CNS NB-FOXR2), and embryonal tumor with multi-layered rosettes (ETMR) are needed for development of differentiated treatment strategies.

METHODS

Within this retrospective, international study, tumor samples of clinically well-annotated patients with the original diagnosis of CNS-PNET were analyzed using DNA methylation arrays (n=307). Additional cases (n=66) with DNA methylation pattern of CNS NB-FOXR2 were included irrespective of initial histological diagnosis. Pooled clinical data (n=292) were descriptively analyzed.

RESULTS

DNA methylation profiling of "CNS-PNET" classified 58(19%) cases as ETMR, 57(19%) as HGG, 36(12%) as CNS NB-FOXR2, and 89(29%) cases were classified into 18 other entities. Sixty-seven (22%) cases did not show DNA methylation patterns similar to established CNS tumor reference classes. Best treatment results were achieved for CNS NB-FOXR2 patients (5-year PFS: 63%±7%, OS: 85%±5%, n=63), with 35/42 progression-free survivors after upfront craniospinal irradiation (CSI) and chemotherapy. The worst outcome was seen for ETMR and HGG patients with 5-year PFS of 18%±6% and 22%±7%, and 5-year OS of 24%±6% and 25%±7%, respectively.

CONCLUSION

The historically reported poor outcome of CNS-PNET patients becomes highly variable when tumors are molecularly classified based on DNA methylation profiling. Patients with CNS NB-FOXR2 responded well to current treatments and a standard-risk-CSI based regimen may be prospectively evaluated. The poor outcome of ETMR across applied treatment strategies substantiates the necessity for evaluation of novel treatments.

Downregulation of both mismatch repair and non-homologous end-joining pathways in hypoxic brain tumour cell lines

Glioblastoma, a grade IV astrocytoma, has a poor survival rate in part due to ineffective treatment options available. These tumours are heterogeneous with areas of low oxygen levels, termed hypoxic regions. Many intra-cellular signalling pathways, including DNA repair, can be altered by hypoxia. Since DNA damage induction and subsequent activation of DNA repair mechanisms is the cornerstone of glioblastoma treatment, alterations to DNA repair mechanisms could have a direct influence on treatment success. Our aim was to elucidate the impact of chronic hypoxia on DNA repair gene expression in a range of glioblastoma cell lines. We adopted a NanoString transcriptomic approach to examine the expression of 180 DNA repair-related genes in four classical glioblastoma cell lines (U87-MG, U251-MG, D566-MG, T98G) exposed to 5 days of normoxia (21% O₂), moderate (1% O₂) or severe (0.1% O₂) hypoxia. We observed altered gene expression in several DNA repair pathways including homologous recombination repair, non-homologous end-joining and mismatch repair, with hypoxia primarily resulting in downregulation of gene expression. The extent of gene expression changes was dependent on hypoxic severity. Some, but not all, of these downregulations were directly under the control of HIF activity. For example, the downregulation of LIG4, a key component of non-homologous end-joining, was reversed upon inhibition of the hypoxia-inducible factor (HIF). In contrast, the downregulation of the mismatch repair gene, PMS2, was not affected by HIF inhibition. This suggests that numerous molecular mechanisms lead to hypoxia-induced reprogramming of the transcriptional landscape of DNA repair. Whilst the global impact of hypoxia on DNA repair gene expression is likely to lead to genomic instability, tumorigenesis and reduced sensitivity to anti-cancer treatment, treatment re-sensitising might require additional approaches to a simple HIF inhibition.

Advanced molecular pathology for rare tumours: A national feasibility study and model for centralised medulloblastoma diagnostics

Aims

Application of advanced molecular pathology in rare tumours is hindered by low sample numbers, access to specialised expertise/technologies and tissue/assay QC and rapid reporting requirements. We assessed the feasibility of co‐ordinated real‐time centralised pathology review (CPR), encompassing molecular diagnostics and contemporary genomics (RNA‐seq/DNA methylation‐array).

Methods

This nationwide trial in medulloblastoma (<80 UK diagnoses/year) introduced a national reference centre (NRC) and assessed its performance and reporting to World Health Organisation standards. Paired frozen/formalin‐fixed, paraffin‐embedded tumour material were co‐submitted from 135 patients (16 referral centres).

Results

Complete CPR diagnostics were successful for 88% (120/135). Inadequate sampling was the most common cause of failure; biomaterials were typically suitable for methylation‐array (129/135, 94%), but frozen tissues commonly fell below RNA‐seq QC requirements (53/135, 39%). Late reporting was most often due to delayed submission. CPR assigned or altered histological variant (vs local diagnosis) for 40/135 tumours (30%). Benchmarking/QC of specific biomarker assays impacted test results; fluorescent in‐situ hybridisation most accurately identified high‐risk MYC/MYCN amplification (20/135, 15%), while combined methods (CTNNB1/chr6 status, methylation‐array subgrouping) best defined favourable‐risk WNT tumours (14/135; 10%). Engagement of a specialist pathologist panel was essential for consensus assessment of histological variants and immunohistochemistry. Overall, CPR altered clinical risk‐status for 29% of patients.

Conclusion

National real‐time CPR is feasible, delivering robust diagnostics to WHO criteria and assignment of clinical risk‐status, significantly altering clinical management. Recommendations and experience from our study are applicable to advanced molecular diagnostics systems, both local and centralised, across rare tumour types, enabling their application in biomarker‐driven routine diagnostics and clinical/research studies.

Reporting morbidity associated with pediatric brain tumor surgery: are the available scoring systems sufficient?

OBJECTIVE

Complications in pediatric neurooncology surgery are seldom and inconsistently reported. This study quantifies surgical morbidity after pediatric brain tumor surgery from the last decade in a single center, using existing morbidity and outcome measures.

METHODS

The authors identified all pediatric patients undergoing surgery for an intracranial tumor in a single tertiary pediatric neurosurgery center between January 2008 and December 2018. Complications between postoperative days 0 and 30 that had been recorded prospectively were graded using appropriate existing morbidity scales, i.e., the Clavien-Dindo (CD), Landriel, and Drake scales. The result of surgery with respect to the predetermined surgical aim was also recorded.

RESULTS

There were 477 cases (364 craniotomies and 113 biopsies) performed on 335 patients (188 males, median age 9 years). The overall 30-day mortality rate was 1.26% (n = 6), and no deaths were a direct result of surgical complication. Morbidity on the CD scale was 0 in 55.14%, 1 in 10.69%, 2 in 18.66%, 3A in 1.47%, 3B in 11.74%, and 4 in 1.05% of cases. Morbidity using the Drake classification was observed in 139 cases (29.14%). Neurological deficit that remained at 30 days was noted in 8.39%; 78% of the returns to the operative theater were for CSF diversion.

CONCLUSIONS

To the authors' knowledge, this is the largest series presenting outcomes and morbidity from pediatric brain tumor surgery. The mortality rate and morbidity on the Drake classification were comparable to those of published series. An improved tool to quantify morbidity from pediatric neurooncology surgery is necessary.

Neuroblastoma: the association of anatomical tumour site, molecular biology and patient outcomes

BACKGROUND

Numerous factors have been identified as carrying prognostic value in neuroblastoma (NB) and therefore incorporated in risk stratification of disease. Here, we investigate the association of anatomical site of NB with molecular biology and clinical outcomes.

METHODS

A total of 117 patients with NB were studied over a 30-year period. Tumour location was confirmed with computed tomography/magnetic resonance imaging. Data on molecular biology were obtained as testing became available. Chi-squared, Fisher's exact test and Kaplan-Meier log-rank tests were used for statistical analysis.

RESULTS

Tumour originated in the thoracic region (thoracic NB, TNB) in 15 patients (13%), adrenal gland (adrenal NB, ANB) in 88 patients (75%) and abdominal/paravertebral chain (paravertebral NB, PVNB) in 14 patients (12%). Overall survival (OS) for ANB was significantly lower (38%; P = 0.015). ANB cases were more frequently diagnosed at stage IV (69%; P = 0.001). MYCN amplification was noted in 33% of ANB cases and associated with lower OS (17% versus 62% MYCN non-amplified ANB; P = 0.01). The vast majority of TNB and PVNB were non-MYCN amplified (100% and 86%, respectively) and carried better prognosis (OS 86% and 83%, respectively). Forty-two percent of ANB cases were diploid and had lower OS (20% versus 71% hyperdiploid ANB; P = 0.079). TNB and PVNB were found to be mostly hyperdiploid (86% and 100%, respectively) with better OS (83% and 33%, respectively). Segmental chromosomal alterations had prognostic significance in those with PVNB (P = 0.03).

CONCLUSION

TNB tumours have better outcomes than adrenal tumours. This may be due to varied factors reported here including non-metastatic disease at presentation, non-amplification of the MYCN oncogene and overall favourable molecular biology characteristics.

Ataxia and mobility in children following surgical resection of posterior fossa tumour: A longitudinal cohort study

PURPOSE

To report the course of ataxia in children up to 2 years post-operatively, following surgical resection of a posterior fossa tumour (PFT).

METHODS

Thirty-five children, (median age 9 years, range 4-15) having resection of PFT, were assessed using the Scale for the Assessment and Rating of Ataxia (SARA), Brief Ataxia Rating Scale (BARS) and the mobility domain of the Paediatric Evaluation of Disability Index (PEDI-m) at initial post-operative period (baseline), 3 months, 1 year and 2 years post-operatively.

RESULTS

Baseline median scores of the SARA and BARS were 8.5 (range 0-35.5), and 7 (0-25) respectively. Ataxia improved at 3 months (median SARA and BARS reduction 3.5 and 4, respectively). Additional gradual improvements in SARA were recorded at 1 (median reduction 2) and 2 years post-operatively (median reduction 0.5). Median baseline PEDI-m was 54.75 (range 15.2-100) with improvement at 3 months (median increase 36.95) and small improvement at 1 year (median increase 2.5) and 2 years (median increase 5.8). Children with medulloblastoma and midline tumours (median baseline SARA 10 and 11, respectively) demonstrated more severe ataxia than children with low-grade gliomas and unilateral tumours (median baseline SARA 7.5 and 6.5, respectively).

CONCLUSION

The largest improvement in ataxia scores and functional mobility scores is demonstrated within the first 3 months post-operatively, but ongoing gradual improvement is observed at 2 years. Children with medulloblastoma and midline tumour demonstrated higher ataxia scores long term.

SURG-12. PAEDIATRIC BRAIN TUMOUR SURGERY: HOW CAN WE REPORT OUR SURGICAL OUTCOMES AND OPERATIVE MORBIDITY?

OBJECTIVE

Our objective was to quantify resection outcomes and operative morbidity in paediatric brain tumour surgery using existing scales, assessing their applicability.

METHODS

We investigated morbidity using the Clavien-Dindo (CD) scale and the Drake classification. All paediatric patients receiving a biopsy or craniotomy for an intracranial tumour in a single tertiary paediatric neurosurgery centre between January 2008 and December 2018 were studied. Complications up to day 30 post op were graded.

RESULTS

There were 459 operations: 92 biopsies and 367 craniotomies comprising 166 infratentorial and 292 supratentorial tumours. Median age was 9 years (56% male). The surgical goal was achieved or exceeded in 94% of cases. Thirty-day mortality was 1.31% with all deaths related to disease and none to surgical complications. The overall CD score was 1 in 10.9% of cases, 2 in 18.9%, 3A in 1.7%, 3B in 11.8%, and 4 in 1.1%. There was no operative morbidity in 54% of cases. Using the Drake classification, meningitis was seen in 3.92% of cases, seizures in 3.92%, neurological deficit (that persisted at 30 days) in 8.5%, CSF leak in 5.01%, wound infection in 1.96%, haemorrhage 1.75 %, shunt infection in 1.53%, shunt block in 0.65%, medical complications in 2.4%, and others in 3.05%.

CONCLUSIONS

This is the largest series presenting morbidity from paediatric brain tumour surgery, and the first to validate the CD scale. Our morbidity on the Drake scale was comparable with other series. There is a need to develop improved tools to quantify morbidity in this high-risk specialty.

MBRS-44. TIME, PATTERN AND OUTCOME OF MEDULLOBLASTOMA RELAPSE ARE ASSOCIATED WITH TUMOUR BIOLOGY AT DIAGNOSIS AND UPFRONT THERAPY: A COHORT STUDY

Disease relapse occurs in ~30% of children with medulloblastoma, and is fatal in the majority. We sought to establish whether clinico-molecular characteristics at diagnosis are associated with the nature of relapse, subsequent disease-course, and whether these associations could inform clinical management. We surveyed the clinical features of medulloblastoma relapse (time-to-relapse, pattern-of-relapse, time-to-death and overall outcome) in 247 centrally-reviewed patients who relapsed following standard-upfront-therapies. We related these to clinico-molecular features at diagnosis, prognostic factors, and first-line/relapse treatment. Patients who received upfront craniospinal irradiation (CSI-treated) displayed prolonged time-to-relapse compared to CSI naïve patients (p<0.001). Similarly, in CSI naïve patients, CSI at relapse, alongside re-resection and desmoplastic/nodular histology, were associated with long-term survival. In CSI-treated patients, the nature of relapse was subgroup-dependent. Local-nodular relapse patterns were enriched in relapsed-MB_SHH patients (p<0.001), but a notable proportion (65%) also acquired distant-diffuse disease (p=0.010). MB_Group3 relapsed quickly (median 1.3 years), MB_Group4 slowly (median 2.1 years). Distant-disease was prevalent in MB_Group3 and MB_Group4 relapses (90%) but, in contrast to relapsed-MB_SHH, nodular and diffuse patterns of distant-disease were observed. Furthermore, nodular disease was associated with a prolonged time-to-death post-relapse (p=0.006). Investigation of second-generation MB_Group3/4 subtypes refined our understanding of heterogeneous relapse characteristics. Subtype VIII had prolonged time-to-relapse; subtype II a rapid time-to-death. Subtypes II/III/VIII developed a significantly higher incidence of distant-disease at relapse, whereas subtypes V/VII did not. The nature of medulloblastoma relapse are biology and therapy-dependent, providing immediate translational opportunities for improved disease management through biology-directed surveillance, post-relapse prognostication and risk-stratified selection of second-line treatment.

IMG-06. PREDICTING SURVIVAL FROM PERFUSION AND DIFFUSION MRI BY MACHINE LEARNING

INTRODUCTION

Magnetic Resonance Imaging (MRI) is routinely used in the assessment of children’s brain tumours. Reduced diffusion and increased perfusion on MRI are commonly associated with higher grade but there is a lack of quantitative data linking these parameters to survival. Machine learning is increasingly being used to develop diagnostic tools but its use in survival analysis is rare. In this study we combine quantitative parameters from diffusion and perfusion MRI with machine learning to develop a model of survival for paediatric brain tumours. METHOD: 69 children from 4 centres (Birmingham, Liverpool, Nottingham, Newcastle) underwent MRI with diffusion and perfusion (dynamic susceptibility contrast) at diagnosis. Images were processed to form ADC, cerebral blood volume (CBV) and vessel leakage correction (K2) parameter maps. Parameter mean, standard deviation and heterogeneity measures (skewness and kurtosis) were calculated from tumour and whole brain and used in iterative Bayesian survival analysis. The features selected were used for k-means clustering and differences in survival between clusters assessed by Kaplan-Meier and Cox-regression.

RESULTS

Bayesian analysis revealed the 5 top features determining survival to be tumour volume, ADC kurtosis, CBV mean, K2 mean and whole brain CBV mean. K-means clustering using these features showed two distinct clusters (high- and low-risk) which bore significantly different survival characteristics (Hazard Ratio = 5.6).

DISCUSSION AND CONCLUSION

Diffusion and perfusion MRI can be used to aid the prediction of survival in children’s brain tumours. Tumour perfusion played a particularly important role in predicting survival despite being less routinely measured than diffusion.

SWK-07. A MULTINATIONAL SURVEY OF PAEDIATRIC NEURO-ONCOLOGY SERVICES: A EUROPEAN RESEARCH NETWORK (ERN) PAEDCAN PROJECT

BACKGROUND

Brain tumours are clinically and biologically highly diverse and account for 25% of paediatric neoplasms. They carry the highest mortality and morbidity of tumour groups. Their management presents significant challenges with performing modern diagnostic assessments, applying multimodal treatment and establishing interdisciplinary cooperation. Outcomes across Europe differ significantly with varying 5year survival reports of 42–79%. This SIOP-Europe PaedCan survey assessed the structures and facilities for individual states and highlight areas for cooperation and support. DESIGN: An online questionnaire was sent to SIOP-Europe Brain Tumour Group members. This had 55 questions assessing pathology, staging, surgery, radiotherapy and paediatric oncology infrastructure. For analysis of the data we divided countries into lower and higher economic status according to GDP (World Bank 2019) with a cut off of $30,100.

RESULTS

There were 388 respondents from 44 countries in 181 different institutions. In the lower GDP group we noted decreased access to biological characterisation of tumours and interdisciplinary tumour boards. In this group of nations, patients were less likely to have treatment by a paediatric specialist neurosurgeon, paediatric neuro-oncologist, neuroradiologist, and paediatric radiation oncologist. There was also less availability to perform early MRI (ventilated) and less access to proton beam therapy. This study supports the aim of the ERN to produce a roadmap document with specific standards and publish guidelines for all relevant diagnostic and therapeutic components of care. The ERN also aims to identify a network of institutions to provide patient advice and training to equalise treatment and outcomes for all children across Europe.

COVD-03. IMPACT OF COVID-19 ON THERAPY PROVISION FOR CHILDREN WITH CNS TUMOURS

INTRODUCTION

The COVID-19 pandemic has led to widespread change in the delivery of rehabilitation. The Teenage Cancer Trust reported that 69% of young people with cancer saw their physiotherapist less than usual during the pandemic raising concerns about physiotherapy input.

METHODS

Retrospective analysis of all children’s therapy input managed under the Neuro Oncology Rehabilitation Team (NORT) between 1^st April and 30^th July 2020. Descriptive analysis of change to physiotherapy provision during this time period by Tertiary and local community services.

RESULTS

49 children were managed under the NORT Therapy Team during this timeframe. 9 children were newly diagnosed with CNS tumours. There was no impact on inpatient therapy provision, 3 had delayed local therapy provision on discharge requiring increased virtual input by the Tertiary centre. 40 children were outpatients managed under the NORT therapy team. 16 children were also receiving regular local physiotherapy input prior to the COVID-19 pandemic. 13 of these children subsequently had their local physiotherapy input suspended during this time period, 8 children were offered virtual input as an alternative by the Tertiary centre, 2 children received increased face to face appointments at the Tertiary centre. 14 of the 24 children managed solely under the Tertiary NORT Therapy Team changed to virtual therapy reviews.

DISCUSSION

There is a clear change in therapy provision as a result of the COVID-19 pandemic. Future research should consider the effectiveness of neurorehabilitation conducted virtually and the impact on physical function of reduced local therapy provision in children with CNS tumours.

ETMR-08. INTERNATIONAL CONSENSUS PROTOCOL FOR EMBRYONAL TUMOR WITH MULTILAYER ROSETTES

Embryonal tumors with multilayer rosettes (ETMR) are rare and highly-aggressive central nervous system (CNS) neoplasms which occur primarily in young children and carry a dismal prognosis. To date, no large clinical investigations have been conducted to determine the optimal therapy for ETMR. Data from retrospective case series suggest that our most aggressive standard therapies are not sufficient for cure in the majority of cases. New treatment approaches incorporating pre-clinical data and the known biology of ETMR are therefore urgently needed. A German drug screen using the patient-derived ETMR BT183 cell line and its xenograft revealed anti-tumor activity of topotecan, doxorubicin, and actinomycin D; three agents used infrequently for treating infant CNS tumors. Additional results from a small series of ETMR patients suggest that optimization of induction chemotherapy using these active agents may improve response and survival outcomes. In 2019, an international panel of pediatric neuro-oncology experts convened to advance therapy for ETMR. A consensus protocol was developed incorporating maximal safe surgical resection, induction chemotherapy with active pre-clinical agents, intrathecal chemotherapy, radiotherapy, and high-dose chemotherapy. This international consensus protocol represents the first prospective clinical investigation specific to ETMR and will be available through a treatment registry globally and as a clinical trial at select centers. The study aims to improve survival by providing aggressive, optimized therapy for ETMR and will serve as a platform to explore new biologically-promising agents. The investigation will also provide valuable prospective outcome data and correlative biological studies to serve as baseline comparators for future clinical trials.

QOL-21. DEVELOPMENT AND UTILISATION OF A NEURO-ONCOLOGY REHABILITATION TEAM: 2018–2019 UPDATE

INTRODUCTION

A multi-disciplinary Neuro-Oncology Rehabilitation Team (NORT) was established at our institution in 2014. We reviewed NORT inputs, processes and outputs in 2018 to 2019 compared to our previously presented data from 2015, soon after service inception.

METHODS

Retrospective analysis of patients who received NORT input June 2018 - May 2019 compared to 2015 data. Descriptive analysis of changes to NORT operational processes and structure. Complexity of rehabilitation needs was measured using the Rehabilitation Complexity Scale-Extended V13 (RCS).

RESULTS

54 children received NORT input in 2018–2019 (10 children in 2015) with total of 129 outputs. NORT input was highest in children with high grade glioma (median reviews: 3; median RCS: 5) and ependymoma (median reviews: 3; median RCS: 5). Pilocytic astrocytoma formed the largest tumour group (n = 11; median reviews: 2; median RCS: 7). 11% patients were referred to neurologist (9% already known); 17% referred to community services (44% already known); 31% referred to neuropsychology. In 2015, outputs were predominantly referral to occupational therapy and physiotherapy. 6 patients (11% of 54) were discharged in 2018–2019 (40% of 10 patients in 2015). 4 patients died. Between 2015 and 2019, developments included: clarifying referral and discharge pathways, use of screening measures, neuropsychology integration, therapy-led drop-in clinics, use of RCS-E. DISCUSSION: There has been a clear increase in utilisation and scope of work of NORT over last 4 years. The strength of this team is multidisciplinary working and expertise. Further developments planned: multidisciplinary rehabilitation interventions and NORT outcome tools.

Time, pattern, and outcome of medulloblastoma relapse and their association with tumour biology at diagnosis and therapy: a multicentre cohort study

Background

Disease relapse occurs in around 30% of children with medulloblastoma, and is almost universally fatal. We aimed to establish whether the clinical and molecular characteristics of the disease at diagnosis are associated with the nature of relapse and subsequent disease course, and whether these associations could inform clinical management.

Methods

In this multicentre cohort study we comprehensively surveyed the clinical features of medulloblastoma relapse (time to relapse, pattern of relapse, time from relapse to death, and overall outcome) in centrally reviewed patients who relapsed following standard upfront therapies, from 16 UK Children's Cancer and Leukaemia Group institutions and four collaborating centres. We compared these relapse-associated features with clinical and molecular features at diagnosis, including established and recently described molecular features, prognostic factors, and treatment at diagnosis and relapse.

Findings

247 patients (175 [71%] boys and 72 [29%] girls) with medulloblastoma relapse (median year of diagnosis 2000 [IQR 1995–2006]) were included in this study. 17 patients were later excluded from further analyses because they did not meet the age and treatment criteria for inclusion. Patients who received upfront craniospinal irradiation (irradiated group; 178 [72%] patients) had a more prolonged time to relapse compared with patients who did not receive upfront craniospinal irradiation (non-irradiated group; 52 [21%] patients; p<0·0001). In the non-irradiated group, craniospinal irradiation at relapse (hazard ratio [HR] 0·27, 95% CI 0·11–0·68) and desmoplastic/nodular histology (0·23, 0·07–0·77) were associated with prolonged time to death after relapse, MYC amplification was associated with a reduced overall survival (23·52, 4·85–114·05), and re-resection at relapse was associated with longer overall survival (0·17, 0·05–0·57). In the irradiated group, patients with MB_Group3 tumours relapsed significantly more quickly than did patients with MB_Group4 tumours (median 1·34 [0·99–1·89] years vs 2·04 [1·39–3·42 years; p=0·0043). Distant disease was prevalent in patients with MB_Group3 (23 [92%] of 25 patients) and MB_Group4 (56 [90%] of 62 patients) tumour relapses. Patients with distantly-relapsed MB_Group3 and MB_Group4 displayed both nodular and diffuse patterns of disease whereas isolated nodular relapses were rare in distantly-relapsed MB_SHH (1 [8%] of 12 distantly-relapsed MB_SHH were nodular alone compared with 26 [34%] of 77 distantly-relapsed MB_Group3 and MB_Group4). In MB_Group3 and MB_Group4, nodular disease was associated with a prolonged survival after relapse (HR 0·42, 0·21–0·81). Investigation of second-generation MB_Group3 and MB_Group4 molecular subtypes refined our understanding of heterogeneous relapse characteristics. Subtype VIII had prolonged time to relapse and subtype II had a rapid time from relapse to death. Subtypes II, III, and VIII developed a significantly higher incidence of distant disease at relapse whereas subtypes V and VII did not (equivalent rates to diagnosis).

Interpretation

This study suggests that the nature and outcome of medulloblastoma relapse are biology and therapy-dependent, providing translational opportunities for improved disease management through biology-directed disease surveillance, post-relapse prognostication, and risk-stratified selection of second-line treatment strategies.

Funding

Cancer Research UK, Action Medical Research, The Tom Grahame Trust, The JGW Patterson Foundation, Star for Harris, The Institute of Child Health - Newcastle University - Institute of Child Health High-Risk Childhood Brain Tumour Network (co-funded by The Brain Tumour Charity, Great Ormond Street Children's Charity, and Children with Cancer UK).

The molecular landscape and associated clinical experience in infant medulloblastoma: prognostic significance of second-generation subtypes

AIMS

Biomarker-driven therapies have not been developed for infant medulloblastoma (iMB). We sought to robustly sub-classify iMB, and proffer strategies for personalized, risk-adapted therapies.

METHODS

We characterized the iMB molecular landscape, including second-generation subtyping, and the associated retrospective clinical experience, using large independent discovery/validation cohorts (n = 387).

RESULTS

iMB_Grp3 (42%) and iMB_SHH (40%) subgroups predominated. iMB_Grp3 harboured second-generation subtypes II/III/IV. Subtype II strongly associated with large-cell/anaplastic pathology (LCA; 23%) and MYC amplification (19%), defining a very-high-risk group (0% 10yr overall survival (OS)), which progressed rapidly on all therapies; novel approaches are urgently required. Subtype VII (predominant within iMB_Grp4 ) and subtype IV tumours were standard risk (80% OS) using upfront CSI-based therapies; randomized-controlled trials of upfront radiation-sparing and/or second-line radiotherapy should be considered. Seventy-five per cent of iMB_SHH showed DN/MBEN histopathology in discovery and validation cohorts (P < 0.0001); central pathology review determined diagnosis of histological variants to WHO standards. In multivariable models, non-DN/MBEN pathology was associated significantly with worse outcomes within iMB_SHH . iMB_SHH harboured two distinct subtypes (iMB_SHH-I/II ). Within the discriminated favourable-risk iMB_SHH DN/MBEN patient group, iMB_SHH-II had significantly better progression-free survival than iMB_SHH-I , offering opportunities for risk-adapted stratification of upfront therapies. Both iMB_SHH-I and iMB_SHH-II showed notable rescue rates (56% combined post-relapse survival), further supporting delay of irradiation. Survival models and risk factors described were reproducible in independent cohorts, strongly supporting their further investigation and development.

CONCLUSIONS

Investigations of large, retrospective cohorts have enabled the comprehensive and robust characterization of molecular heterogeneity within iMB. Novel subtypes are clinically significant and subgroup-dependent survival models highlight opportunities for biomarker-directed therapies.

Neutrophil function is impaired in paediatric patients with malignancy and may be a useful clinical marker

PURPOSE

Patients treated with cytotoxic chemotherapy are at risk of neutropenia, neutropenic fever and neutropenic sepsis. We hypothesised that pre-existing neutrophil function dysfunction may increase susceptibility to neutropenic fever in paediatric patients receiving cytotoxic chemotherapy.

METHODS

Prospective cohort study recruited patients at Alder Hey Children's NHS Foundation Trust, United Kingdom. We measured neutrophil phagocytic function using a validated flow cytometric whole blood phagocytosis assay in paediatric patients (n = 16) with oncological disease before and after chemotherapy in a prospective cohort study. We recruited healthy children as a control comparator (n = 10).

RESULTS

We found significantly decreased phagocytic function in oncology patients compared to healthy participants. In five patients who developed neutropenic fever, we observed increased pre-dose neutrophil respiratory burst.

CONCLUSION

With further validation, measurement of neutrophil function could potentially be used to personalise appropriate prophylactic antimicrobial administration for patients receiving cytotoxic chemotherapy.

BET inhibition therapy counteracts cancer cell survival, clonogenic potential and radioresistance mechanisms in rhabdomyosarcoma cells

The antitumour effects of OTX015, a first-in-class BET inhibitor (BETi), were investigated as a single agent or in combination with ionizing radiation (IR) in preclinical in vitro models of rhabdomyosarcoma (RMS), the most common childhood soft tissue sarcoma. Herein, we demonstrated the upregulation of BET Bromodomain gene expression in RMS tumour biopsies and cell lines compared to normal skeletal muscle. In vitro experiments showed that OTX015 significantly reduced RMS cell proliferation by altering cell cycle modulators and apoptotic related proteins due to the accumulation of DNA breaks that cells are unable to repair. Interestingly, OTX015 also impaired migration capacity and tumour-sphere architecture by downregulating pro-stemness genes and was able to potentiate ionizing radiation effects by reducing the expression of different drivers of tumour dissemination and resistance mechanisms, including the GNL3 gene, that we correlated for the first time with the RMS phenotype. In conclusion, our research sheds further light on the molecular events of OTX015 action against RMS cells and indicates this novel BETi as an effective option to improve therapeutic strategies and overcome the development of resistant cancer cells in patients with RMS.

Effects of the growth pattern of medulloblastoma on short-term neurological impairments after surgery: results from the prospective multicenter HIT-SIOP PNET 4 study

OBJECTIVE

Extensive resection of a tumor in the posterior fossa in children is associated with the risk of neurological deficits. The objective of this study was to prospectively evaluate the short-term neurological morbidity in children after medulloblastoma surgery and relate this to the tumor's growth pattern and to the extent of resection.

METHODS

In 160 patients taking part in the HIT-SIOP PNET 4 (Hyperfractionated Versus Conventionally Fractionated Radiotherapy in Standard Risk Medulloblastoma) trial, neurosurgeons prospectively responded to questions concerning the growth pattern of the tumor they had resected. The extent of resection (gross, near, or subtotal) was evaluated using MRI. The patients' neurological status before resection and around 30 days after resection was recorded.

RESULTS

Invasive tumor growth, defined as local invasion in the brain or meninges, cranial nerve, or major vessel, was reported in 58% of the patients. After surgery almost 70% of all patients were affected by one or several neurological impairments (e.g., impaired vision, impaired extraocular movements, and ataxia). However, this figure was very similar to the preoperative findings. Invasive tumor growth implied a significantly higher number of impairments after surgery (p = 0.03) and greater deterioration regarding extraocular movements (p = 0.012), facial weakness (p = 0.048), and ataxia in the arms (p = 0.014) and trunk (p = 0.025) compared with noninvasive tumor growth. This deterioration was not dependent on the extent of resection performed. Progression-free survival (PFS) at 5 years was 80% ± 4% and 76% ± 5% for patients with invasive and noninvasive tumor growth, respectively, with no difference in the 5-year PFS for extent of resection.

CONCLUSIONS

Preoperative neurological impairments and invasive tumor growth were strong predictors of deterioration in short-term neurological outcome after medulloblastoma neurosurgery, whereas the extent of resection was not. Neither tumor invasiveness nor extent of resection influenced PFS. These findings support the continuation of maximal safe resection in medulloblastoma surgery where functional risks are not taken in areas with tumor invasion.

E-Survey of Current International Physiotherapy Practice for Children with Ataxia Following Surgical Resection of Posterior Fossa Tumour

Objective

To determine current international practice regarding physiotherapy input for children with ataxia following surgery for posterior fossa tumour. Design: An e-survey covering the following domains: participant demographics, treatment/ intervention, virtual training, intensity/timing of treatment, and aims and outcomes of physiotherapy management.

Participants

Physiotherapists involved in the management of children with ataxia following surgical resection of posterior fossa tumour. Participants were contacted via 6 key groups; Paediatric Oncology Physiotherapy Network (POPs), Association of Paediatric Chartered Physiotherapists (APCP), European Paediatric Neurology Society (EPNS), International Society of Paediatric Oncology (SIOP)-Europe Brain Tumour Group, Posterior Fossa Society (PFS), and Pediatric Oncology Special Interest Group (SIG) (American Physical Therapy Association).

Results

A total of 96 physiotherapists participated: UK (n =53), rest of Europe (n = 23), USA/ Canada (n = 10), and Australia/NZ (n = 10). The most common physiotherapy interventions used were balance exercises, gait re-education and proximal control activities. The most frequently used adjuncts to treatment were mobility aids and orthotics. Challenges reported regarding physiotherapy treatment were: reduced availability of physiotherapy input following discharge from the acute setting, lack of evidence, impact of adjuvant oncology treatment, and psychosocial impact.

Conclusion

This e-survey provides an initial scoping review of international physiotherapy practice in this area. It establishes a foundation for future research on improving rehabilitation of ataxia in this population.

Utilising functional imaging to predict survival in paediatric brain tumours

Introduction

Brain tumours are a common cause of death in the paediatric population. We have previously shown that MR imaging and spectroscopy can be used to non-invasively differentiate between tumour types. Here, we demonstrate that functional imaging can be highly predictive of survival and grade in a paediatric cohort.

Methods

Perfusion (PWI) and diffusion weighted imaging (DWI) were performed in a multi-site (Birmingham Children’s Hospital, Royal Victoria Infirmary, Alder Hey, Nottingham) cohort ([grade, 5-year survival alive:dead number] = [I,15:1],[II, 5:1],[III,2:3],[IV,8:11]). ROIs were drawn on T2 imaging and functional imaging features (mean, standard deviation, skewness, and kurtosis) were derived. Supervised machine learning was used to predict 5-year survival and tumour grade from features. ANOVA and post-hoc tests were used to assess differences in features between grade and 5-year survival status.

Results

5-year survival was predicted with 89%, 85%, and 87% accuracy with all imaging, perfusion, or diffusion features, respectively.

A significant difference in perfusion was found between surviving and diseased participants (1.71 ± 0.82 vs 2.62 ± 1 mL/100g/min, respectively, p < 0.05). A significant difference in ADC (mm2 s-1) between tumour grades was found (1 vs 4 (1533 ± 458 vs 857 ± 239), 4 vs 3 (857 ± 239 vs 1197 ± 137), 4 vs 2 (857 ± 239 vs 1440 ± 557), corrected p < 0.05).

Conclusion

We have shown that perfusion and diffusion imaging features can be used to non-invasively assess tumour grade and estimate 5-year survival status in a cohort of paediatric brain tumours.