Postoperative cerebellar mutism syndrome is an acquired autism-like network disturbance

BACKGROUND

Cerebellar mutism syndrome (CMS) is a common and debilitating complication of posterior fossa tumor surgery in children. Affected children exhibit communication and social impairments that overlap phenomenologically with subsets of deficits exhibited by children with Autism spectrum disorder (ASD). Although both CMS and ASD are thought to involve disrupted cerebro-cerebellar circuitry, they are considered independent conditions due to an incomplete understanding of their shared neural substrates.

METHODS

In this study, we analyzed postoperative cerebellar lesions from 90 children undergoing posterior fossa resection of medulloblastoma, 30 of whom developed CMS. Lesion locations were mapped to a standard atlas, and the networks functionally connected to each lesion were computed in normative adult and pediatric datasets. Generalizability to ASD was assessed using an independent cohort of children with ASD and matched controls (n = 427).

RESULTS

Lesions in children who developed CMS involved the vermis and inferomedial cerebellar lobules. They engaged large-scale cerebellothalamocortical circuits with a preponderance for the prefrontal and parietal cortices in the pediatric and adult connectomes, respectively. Moreover, with increasing connectomic age, CMS-associated lesions demonstrated stronger connectivity to the midbrain/red nuclei, thalami and inferior parietal lobules and weaker connectivity to the prefrontal cortex. Importantly, the CMS-associated lesion network was independently reproduced in ASD and correlated with communication and social deficits, but not repetitive behaviors.

CONCLUSIONS

Our findings indicate that CMS-associated lesions may result in an ASD-like network disturbance that occurs during sensitive windows of brain development. A common network disturbance between CMS and ASD may inform improved treatment strategies for affected children.

Proton Therapy Mediates Dose Reductions to Brain Structures Associated With Cognition in Children With Medulloblastoma

PURPOSE

Emerging evidence suggests proton radiation therapy may offer cognitive sparing advantages over photon radiation therapy, yet dosimetry has not been compared previously. The purpose of this study was to examine dosimetric correlates of cognitive outcomes in children with medulloblastoma treated with proton versus photon radiation therapy.

METHODS AND MATERIALS

In this retrospective, bi-institutional study, dosimetric and cognitive data from 75 patients (39 photon and 36 proton) were analyzed. Doses to brain structures were compared between treatment modalities. Linear mixed-effects models were used to create models of global IQ and cognitive domain scores.

RESULTS

The mean dose and dose to 40% of the brain (D40) were 2.7 and 4.1 Gy less among proton-treated patients compared with photon-treated patients (P = .03 and .007, respectively). Mean doses to the left and right hippocampi were 11.2 Gy lower among proton-treated patients (P < .001 for both). Mean doses to the left and right temporal lobes were 6.9 and 7.1 Gy lower with proton treatment, respectively (P < .001 for both). Models of cognition found statistically significant associations between higher mean brain dose and reduced verbal comprehension, increased right temporal lobe D40 with reduced perceptual reasoning, and greater left temporal mean dose with reduced working memory. Higher brain D40 was associated with reduced processing speed and global IQ scores.

CONCLUSIONS

Proton therapy reduces doses to normal brain structures compared with photon treatment. This leads to reduced cognitive decline after radiation therapy across multiple intellectual endpoints. Proton therapy should be offered to children receiving radiation for medulloblastoma.

Long-term neurocognitive and psychological outcomes in meningioma survivors: Individual changes over time and radiation dosimetry

Background

This study investigates long-term changes in neurocognitive performance and psychological symptoms in meningioma survivors and associations with radiation dose to circumscribed brain regions.

Methods

We undertook a retrospective study of meningioma survivors who underwent longitudinal clinical neurocognitive assessments. Change in neurocognitive performance or psychological symptoms was assessed using reliable change indices. Radiation dosimetry, if prescribed, was evaluated based on treatment-planning computerized tomography co-registered with contrast-enhanced 3D T1-weighted magnetic resonance imaging. Mixed effects analyses were used to explore whether incidental radiation to brain regions outside the tumor influences neurocognitive and psychological outcomes.

Results

Most (range = 41%-93%) survivors demonstrated stable-albeit often below average-neurocognitive and psychological trajectories, although some also exhibited improvements (range = 0%-31%) or declines (range = 0%-36%) over time. Higher radiation dose to the parietal-occipital region (partial R2 = 0.462) and cerebellum (partial R2 = 0.276) was independently associated with slower visuomotor processing speed. Higher dose to the hippocampi was associated with increases in depression (partial R2 = 0.367) and trait anxiety (partial R2 = 0.236).

Conclusions

Meningioma survivors experience neurocognitive deficits and psychological symptoms many years after diagnosis, and a proportion of them decline over time. This study offers proof of concept that incidental radiation to brain regions beyond the tumor site may contribute to these sequelae. Future investigations should include radiation dosimetry when examining risk factors that contribute to the quality of survivorship in this growing population.

Dose Reductions to Critical Brain Organs-at-Risk and Better Cognition in Children with Medulloblastoma Receiving Proton Therapy

PURPOSE/OBJECTIVE(S)

Our group previously demonstrated an improvement in cognition among children with medulloblastoma treated with proton therapy, as compared to photon therapy. However, the reason for this cognitive improvement was unclear. In this study, our aim was to determine whether dose to critical brain structures acted as a mediator of improved cognition in patients treated with proton therapy.

MATERIALS/METHODS

In this retrospective study, a cohort of 75 children with medulloblastoma from two institutions was assembled (39 photon, 36 proton). Included patients were treated with similar radiation and cognitive follow-up protocols. Study endpoints were verbal comprehension (VCI), perceptual reasoning (PRI), working memory (WMI), processing speed (PSI) indices and full-scale IQ (FSIQ). Brain structures were segmented and dose comparisons by RT modality were compared using independent t-tests. Linear mixed effects models with random intercepts were created to evaluate cognitive endpoints using R version 4.2.2.

RESULTS

Median follow-up from RT to last cognitive assessment was 4.8 years. Total dose, including RT boost, was slightly lower in the proton cohort than the photon cohort (mean, 54.6 Gy vs. 56.1 Gy, respectively, p < 0.001). Eleven children (31%) treated with proton therapy received 36 Gy CSI, while 6 children (15%) treated with photon therapy received 36 Gy CSI (p = 0.07). Children treated with proton therapy had reduced total doses to the brain (mean, D40), left and right temporal lobes (mean, D40, D50), and left and right hippocampi (mean, D40, D50 - see Table). After adjustment for age at RT and posterior fossa syndrome, higher whole brain mean dose and time since RT were associated with greater decrease in VCI (p = 0.033), higher left temporal D50 and time since RT with greater decrease in PRI (p = 0.031), higher whole brain D40 and time since RT with greater decrease in PSI (p < 0.001) and FSIQ (p = 0.030).

CONCLUSION

Our study demonstrates that proton therapy for patients with medulloblastoma reduces dose to normal brain tissues, which is associated with better intellectual outcomes. Children with medulloblastoma who undergo RT should be treated with proton therapy, if available.

Cancer neuroscience: State of the field, emerging directions

The nervous system governs both ontogeny and oncology. Regulating organogenesis during development, maintaining homeostasis, and promoting plasticity throughout life, the nervous system plays parallel roles in the regulation of cancers. Foundational discoveries have elucidated direct paracrine and electrochemical communication between neurons and cancer cells, as well as indirect interactions through neural effects on the immune system and stromal cells in the tumor microenvironment in a wide range of malignancies. Nervous system-cancer interactions can regulate oncogenesis, growth, invasion and metastatic spread, treatment resistance, stimulation of tumor-promoting inflammation, and impairment of anti-cancer immunity. Progress in cancer neuroscience may create an important new pillar of cancer therapy.

Homeostatic coordination and up-regulation of neural activity by activity-dependent myelination

Activity-dependent myelination (ADM) is a fundamental dimension of brain plasticity through which myelin changes as a function of neural activity. Mediated by structural changes in glia, ADM notably regulates axonal conduction velocity. Yet, it remains unclear how neural activity impacts myelination to orchestrate the timing of neural signalling, and how ADM shapes neural activity. We developed a model of spiking neurons enhanced with neuron-oligodendrocyte feedback and examined the relationship between ADM and neural activity. We found that ADM implements a homeostatic gain control mechanism that enhances neural firing rates and correlations through the temporal coordination of action potentials as axon lengths increase. Stimuli engage ADM plasticity to trigger bidirectional and reversible changes in conduction delays, as may occur during learning. Furthermore, ADM was found to enhance information transmission under various types of time-varying stimuli. These results highlight the role of ADM in shaping neural activity and communication.

Structural connectivity and intelligence in brain-injured children

In children, higher general intelligence corresponds with better processing speed ability. However, the relationship between structural brain connectivity and processing speed in the context of intelligence is unclear. Furthermore, the impact of brain injury on this relationship is also unknown. Structural networks were constructed for 36 brain tumor patients (mean age: 13.45 ± 2.73, 58% males) and 35 typically developing children (13.30 ± 2.86, 51% males). Processing speed and general intelligence scores were acquired using standard batteries. The relationship between network properties, processing speed, and intelligence was assessed using a partial least squares analysis. Results indicated that structural networks in brain-injured children were less integrated (β = -.38, p = 0.001) and more segregated (β = 0.4, p = 0.0005) compared to typically developing children. There was an indirect effect of network segregation on general intelligence via processing speed, where greater network segregation predicted slower processing speed which in turn predicted worse general intelligence (GoF = 0.37). These findings provide the first evidence of relations between structural connectivity, processing speed, and intelligence in children. Injury-related disruption to the structural network may result in worse intelligence through impacts on information processing. Our findings are discussed in the context of a network approach to understanding brain-behavior relationships.

QOL-28. Clinico-molecular correlates of quality of survival and neurocognitive outcomes in medulloblastoma; a meta-analysis of the SIOP-UKCCSG-PNET3 and HIT-SIOP-PNET4 trials

Determinants of survivorship outcomes are emerging from limited studies of medulloblastoma (MB) survivors. We undertook an integrated analysis of biological (tumour group, host genetics) and clinico-demographic features in patients treated on the SIOP-UKCCSG-PNET3 and HIT-SIOP-PNET4 clinical trials with available quality of survival (QoS) data (n=218), to determine key correlates of survivorship, and their clinical potential. Treatment/demographic factors and molecular subgroup (MBWNT, MBSHH, MBGrp3, MBGrp4) were assessed against health status, behavioural functioning, and health-related quality of life (HrQoL). In DNA from HIT-SIOP-PNET4 (n=74), 39 candidate SNPs with known modifying effects on neurocognitive outcomes (e.g., involved in oxidative stress/inflammation) were genotyped and assessed against Wechsler Intelligence Scale (WISC) scores. As expected, MBSHH was associated with improved HrQoL, but subgroup did not associate further with QoS outcomes. SIOP-UKCCSG-PNET3 patients receiving chemotherapy before craniospinal irradiation (CSI) had significantly lower health status (p=0.021) and behavioural functioning (p&lt;0.016) compared to patients treated with CSI alone, and those treated on both arms (maintenance chemotherapy and hyperfractionated (36Gy) or standard (23.4Gy) CSI) of HIT-SIOP-PNET4. SIOP-UKCCSG-PNET3 patients receiving CSI-only had better HrQoL scores than those who received pre-CSI chemotherapy and both HIT-SIOP-PNET4 arms (p=0.004). Females reported worse HrQoL/behavioural functioning across both trials (p&lt;0.04). In HIT-SIOP-PNET4, longer intervals from diagnosis to CSI predicted worse HrQoL/health status (p&lt;0.05). Neither molecular group nor clinico-demographic features tested were associated with neurocognition. In contrast, 6 SNPs significantly associated with ≥1 WISC domain; 4/6 showed multiple associations and were independently prognostic; further associations were apparent at the gene/pathway level. This large, integrated and multi-disciplinary analysis of two independent trials cohorts has revealed multiple factors predictive of medulloblastoma survivorship including treatment (chemotherapy, time to CSI), tumour (molecular group) and host genetic factors. Assessment in further prospective series are required to determine their potential as a basis for modifications to disease management.

INSP-06. Recent advances in improving neuropsychological outcomes for paediatric brain tumour patients - Are we entering a new era?

Children and youth treated for brain tumours can sustain a brain injury as a consequence of the tumour and curative therapy leaving them with significant cognitive challenges. Advances in treatment for paediatric brain tumours – particularly the delivery of radiotherapy – have been associated with improved neuropsychological outcome in survivors, however. This presentation will first focus on work documenting the impact of changes in cranial radiotherapy delivery and modality on neuropsychological late effects in children treated for medulloblastoma. Outcomes in patients treated on modern protocols are substantially improved relative to prior therapy, however challenges remain. Second, novel approaches for cognitive recovery and brain repair in survivors of paediatric brain tumours will be discussed, with a focus on novel approaches for fostering endogenous neuroplasticity for cognitive recovery and brain repair in children and youth treated for paediatric brain tumours.

Abnormalities of Structural Brain Connectivity in Pediatric Brain Tumor Survivors

Background

Pediatric brain tumor survivors are at an increased risk for white matter (WM) injury. However, damage to whole-brain structural connectivity is unelucidated. The impact of treatment on WM connectivity was investigated.

Methods

Whole-brain WM networks were derived from diffusion tensor imaging data acquired for 28 irradiated patients (radiotherapy, RT) (mean age = 13.74 ± 3.32 years), 13 patients not irradiated (No RT) (mean age = 12.57 ± 2.87), and 41 typically developing children (TDC) (mean age = 13.32 ± 2.92 years). Differences in network properties were analyzed using robust regressions.

Results

Participation coefficient was lower in both patient groups (RT: adj. P = .015; No RT: adj. P = .042). Compared to TDC, RT had greater clustering (adj. P = .015), local efficiency (adj. P = .003), and modularity (adj. P = .000003). WM traced from hubs was damaged in patients: left hemisphere pericallosal sulcus (FA [F = 4.97; q < 0.01]; MD [F = 11.02; q < 0.0001]; AD [F = 10.00; q < 0.0001]; RD [F = 8.53; q < 0.0001]), right hemisphere pericallosal sulcus (FA [F = 8.87; q < 0.0001]; RD [F = 8.27; q < 0.001]), and right hemisphere parietooccipital sulcus (MD [F = 5.78; q < 0.05]; RD [F = 5.12; q < 0.05]).

Conclusions

Findings indicate greater segregation of WM networks after RT. Intermodular connectivity was lower after treatment with and without RT. No significant network differences were observed between patient groups. Our results are discussed in the context of a network approach that emphasizes interactions between brain regions.

Progressive retinal changes in pediatric multiple sclerosis

Objectives To determine to what extent acute demyelinating episodes versus chronic degenerative phenomena drive retinal neuroaxonal damage in pediatric acquired demyelinating syndromes (ADS). Methods We acquired optical coherence tomography (OCT) data (follow-up range: 2 weeks - 5 years, at variable intervals from presentation) in pediatric participants who had multiple sclerosis (MS), monophasic ADS, or were healthy. Multivariable mixed effects models were used to assess the association of the number of demyelinating episodes (either optic neuritis [ON], or non-ON relapses) with changes in retinal nerve fiber layer (RNFL) or ganglion cell layer-inner plexiform layer (GCIPL) thickness. Results 64 OCT sans from 23 MS, and 33 scans from 12 monophasic ADS participants were compared with 68 scans from 62 healthy participants. The first ON episode had the biggest impact on RNFL or GCIPL thickness in monophasic ADS (RNFL: -7.9 µm, CI=5.5, p = 0.0056; GCIPL: -8.4 µm, CI=4.4, p = 0.0002) and MS (RNFL: -16 µm, CI = 3.7, p < 10^-6; GCIPL: -15 µm, CI = 2.6, p < 10^-6). Non-ON relapses were also associated with small but significant retinal thickness reductions in MS (RNFL: -2.6 µm/relapse, CI = 1.4, p = 0.0003; GCIPL: -2.8 µm/relapse, CI = 0.89, p < 10^-6). MS participants showed progressive GCIPL thinning independent of acute demyelinating episodes (-2.7 µm/year, CI = 1.9, p = 0.0058). Conclusions We showed a prominent impact of early ON episodes on OCT measures of neuroaxonal structure in patients with ADS. We also demonstrated negative effects of non-ON relapses, and the presence of chronic retinal neurodegenerative changes, in youth with MS.

Radiation dose to circumscribed brain regions and neurocognitive function in patients with meningioma

Background

Although radiation (RT) is standard treatment for many brain tumors, it may contribute to neurocognitive decline. The objective of this study was to investigate associations between RT dose to circumscribed brain regions and specific neurocognitive domains in patients with meningioma.

Methods

We undertook a retrospective study of 40 patients with meningioma who received RT and underwent an in-depth clinical neurocognitive assessment. Radiation dosimetry characteristics were delineated based on treatment planning computerized tomography co-registered with contrast-enhanced 3D T1-weighted magnetic resonance imaging. Principal components analysis was applied to organize neurocognitive test scores into factors, and multivariate multiple linear regression models were undertaken to examine if RT dose to circumscribed brain regions is associated with specific neurocognitive outcomes.

Results

Radiation dose to brain regions was associated with neurocognitive functions across a number of domains. High dose to the parietal-occipital region was associated with slower visuomotor processing speed (mean dose, β = -1.100, P = .017; dose to 50% of the region [D50], β = -0.697, P = .049). In contrast, high dose to the dorsal frontal region was associated with faster visuomotor processing speed (mean dose, β = 0.001, P = .036).

Conclusions

These findings suggest that RT delivered to brain regions (ie, parietal-occipital areas) may contribute to poor neurocognitive outcomes. Given that modern radiotherapy techniques allow for precise targeting of dose delivered to brain regions, prospective trials examining relations between dose and neurocognitive functions are warranted to confirm these preliminary results.

Long-term neurocognitive, psychological, and return to work outcomes in meningioma patients

INTRODUCTION

This study aimed to investigate long-term neurocognitive, psychological, and return to work (RTW) outcomes in meningioma patients, and to explore whether neurocognitive and psychological factors influence RTW outcomes in this population.

METHODS

In this retrospective study, 61 meningioma patients completed in-depth clinical neuropsychological assessments. Of these participants, 42 were of working-age and had RTW information available following neuropsychological assessment. Seventy-one percent and 80% of patients received radiation and surgery, respectively, with 49% receiving both radiation and surgery. Associations between demographic, medical, neurocognitive, psychological, and RTW data were analyzed using multivariable logistic regression analyses.

RESULTS

In our sample, 68% of patients exhibited global neurocognitive impairment, with the largest effect sizes found on tests of visual memory (d = 0.73), executive function (d = 0.61), and attention (d = 0.54). Twenty-seven percent exhibited moderate to severe levels of depressive symptoms. In addition, 23% and 30% exhibited clinically significant state and trait anxiety, respectively. Forty-eight percent of patients were unable to RTW. Younger age, faster visuomotor processing speed, and, unexpectedly, higher trait anxiety scores were associated with an increased likelihood of returning to work.

CONCLUSIONS

Meningioma patients are at risk of experiencing neurocognitive deficits, psychological symptoms, and difficulties returning to work. Our results suggest that neurocognitive and psychological factors contribute to RTW status in meningioma patients. Prospective research studies are necessary to increase our understanding of the complexity of functional disability in this growing population.

Hearing Loss After Radiation and Chemotherapy for CNS and Head-and-Neck Tumors in Children

PURPOSE

Hearing loss (HL) is a serious secondary effect of treatment for CNS and head-and-neck tumors in children. The goal of this study was to evaluate incidence and risk factors for HL in patients with multiple ototoxic exposures.

PATIENTS AND METHODS

We evaluated 340 ears from 171 patients with CNS or head-and-neck tumors treated with radiation, with or without chemotherapy, who had longitudinal audiologic evaluation. International Society of Pediatric Oncology-Boston grades were assigned to 2,420 hearing assessments. Multivariable weighted ordinal logistic regression was fitted to evaluate the effect of clinicopathologic features on HL.

RESULTS

Mean cochlea dose (odds ratio [OR] 1.04 per Gy, P < .001), time since radiotherapy (RT; OR 1.21 per year, P < .001), cisplatin dose (OR 1.48 per 100 mg/m², P < .001), and carboplatin dose (OR 1.41 per 1,000 mg/m², P = .002) were associated with increasing International Society of Pediatric Oncology-Boston grade of HL. There was no synergistic effect of RT and cisplatin (interaction term, P = .53) or RT and carboplatin (interaction term, P = .85). Cumulative incidence of high-frequency HL (> 4 kHz) was 50% or greater at 5 years after RT if mean cochlea dose was > 30 Gy, while incidence of HL across all frequencies continued to increase beyond 5 years after RT.

CONCLUSION

Children treated with radiation and chemotherapy experience a high incidence of HL over time, with associations found between more severe HL and cisplatin or carboplatin dose as well as mean cochlea dose. Mean cochlea dose of ≤ 30 Gy is proposed as a goal to reduce the risk of HL; a lower threshold (20-25 Gy) may be considered in patients receiving platinum chemotherapy to reduce cumulative HL burden.

Intellectual changes after radiation for children with brain tumors: which brain structures are most important?

BACKGROUND

The objective of this study was to evaluate the contribution of radiation dose to different intracranial structures on changes in intellectual function for children with brain tumors.

METHODS

We evaluated children with brain tumors treated in 2005-2017 who had longitudinal neuropsychological assessments and available photon dosimetric data (if radiation therapy [RT] given). Full Scale Intelligence Quotient (FSIQ) and index scores were evaluated (perceptual reasoning index [PRI], processing speed index [PSI], verbal comprehension index [VCI], and working memory index [WMI]). Multivariable linear mixed effects models were used to model endpoints, with age at RT and dose to different brain regions as fixed effects and patient-specific random intercepts. P-values (P*) were adjusted for multiple comparisons.

RESULTS

Sixty-nine patients were included, 56 of whom received RT. Median neuropsychological follow-up was 3.2 years. Right temporal lobe mean dose was strongly associated with decline in FSIQ (P* = 0.005); with each gray increase in mean dose, there was a decrease of 0.052 FSIQ points per year. Dose to 50% (D50) of the supratentorial brain was associated with decline in PSI (P* = 0.006) and WMI (P* = 0.001). Right and left hippocampus D50 were individually strongly associated with declines in VCI (P* = 0.009 for each). Presence of a ventriculoperitoneal shunt decreased FSIQ by 10 points.

CONCLUSIONS

We reported associations between dosimetry to specific brain regions and intellectual outcomes, with suggested avoidance structures during RT planning. These models can help clinicians anticipate changes in neurocognition post-RT and guide selection of an optimal RT plan.

RONC-03. NEUROCOGNITIVE CHANGES AFTER RADIATION FOR PEDIATRIC BRAIN TUMOURS: WHICH BRAIN SUBSTRUCTURES ARE MOST IMPORTANT?

INTRODUCTION

The contribution of different intracranial structures on neurocognitive decline after radiation therapy (RT) in children is unclear.

METHODS

This was a retrospective study of children with brain tumours treated from 2005 to 2017. Patients with longitudinal neurocognitive assessments and photon dosimetric data (if RT given) were included. Full scale intelligence quotient (FSIQ) was the primary endpoint; sub-indices of neurocognition were modelled separately (perceptual reasoning [PRI], processing speed [PSI], verbal comprehension [VCI] and working memory [WMI]). Multivariable linear mixed effects models were used to model endpoints, with age at diagnosis & dose to different brain regions as fixed effects and patient-specific random intercepts.

RESULTS

Sixty-nine patients were included; ten patients did not receive any RT (i.e. low-grade glioma). Median neurocognitive follow-up was 3.2 years. Right hippocampus mean dose was a strong predictor of declines in FSIQ (p < .001), VCI (p = 0.002) and PRI (p = 0.049). Dose to 50% of the supratentorial brain (D50) was the strongest predictor for WMI (p < .001) and PSI (p < .001). Each gray increase in mean right hippocampus dose resulted in a decrease of 0.038 FSIQ points/year. After adjusting for dose to brain substructures, younger age & presence of a ventriculoperitoneal shunt were also associated with decreased FSIQ.

CONCLUSIONS

Mean dose to the right hippocampus was associated with declines in FSIQ, VCI and PRI, while supratentorial brain D50 was associated with WMI and PSI. Efforts should be made to reduce unnecessary dose to these brain structures.

QOL-01. LONGITUDINAL COMPARISON OF NEUROCOGNITIVE TRAJECTORIES IN PEDIATRIC MEDULLOBLASTOMA PATIENTS TREATED WITH PROTON VERSUS PHOTON RADIOTHERAPY

PURPOSE

By reducing dose to normal brain tissue, proton radiotherapy (PRT) may lessen neurocognitive risk traditionally associated with photon radiotherapy (XRT). We examined change in neurocognitive scores over time in pediatric medulloblastoma patients treated with PRT versus XRT.

METHODS

Neurocognitive scores from 79 patients (37 PRT, 42 XRT) were examined. Patients were treated between 2007–2018 on the same treatment protocols that differed only by craniospinal modality (PRT versus XRT). Change in scores over time since diagnosis were compared between groups.

RESULTS

Groups were similar on most demographic/clinical variables: sex (67.1% male), age at diagnosis (mean 8.6 years), CSI dose (median 23.4 Gy), length of follow-up (mean 4.3 years), and parental education (mean 14.3 years). Boost dose (p<0.001) and margin (p=0.001) differed between groups. Adjusting for covariates, the PRT group exhibited superior outcomes in global IQ, perceptual reasoning, and working memory versus the XRT group (all p<0.05). The XRT group exhibited significant decline in global IQ, working memory, and processing speed (all p<0.05). The PRT group exhibited stable scores in all domains except processing speed (p=0.003). Posterior fossa syndrome imparted risk independent of modality.

CONCLUSION

This is the first study comparing neurocognitive trajectories between pediatric patients treated for medulloblastoma with PRT versus XRT on comparable, contemporary protocols. PRT was associated with more favorable neurocognitive outcomes in most domains compared to XRT, although processing speed emerged as vulnerable in both groups. This is the strongest evidence to date of an intellectual sparing advantage with PRT in the treatment of pediatric medulloblastoma.

QOL-09. WHOLE-BRAIN WHITE MATTER NETWORK CONNECTIVITY IS DISRUPTED BY PEDIATRIC BRAIN TUMOR TREATMENT

INTRODUCTION

Treatments for pediatric brain tumors (PBT) are neurotoxic and lead to long-term deficits that are driven by the perturbation of underlying white matter (WM). It is unclear if and how treatment may impair WM connectivity across the entire brain.

METHODS

Magnetic resonance images from 41 PBT survivors (mean age: 13.19 years, 53% M) and 41 typically developing (TD) children (mean age: 13.32 years, 51% M) were analyzed. Image reconstruction, segmentation, and node parcellation were completed in FreeSurfer. DTI maps and probabilistic streamline generation were completed in MRtrix3. Connectivity matrices were based on the number of streamlines connecting two nodes and the mean DTI (FA) index across streamlines. We used graph theoretical analyses to define structural differences between groups, and random forest (RF) analyses to identify hubs that reliably classify PBT and TD children.

RESULTS

For survivors treated with radiation, betweeness centrality was greater in the left insular (p &lt; 0.000) but smaller in the right pallidum (p &lt; 0.05). For survivors treated without radiation (surgery-only), betweeness centrality was smaller in the right interparietal sulcus (p &lt; 0.05). RF analyses showed that differences in WM connectivity from the right pallidum to other parts of the brain reliably classified PBT survivors from TD children (classification accuracy = 77%).

CONCLUSIONS

The left insular, right pallidum, and right inter-parietal sulcus are structurally perturbed hubs in PBT survivors. WM connectivity from the right pallidum is vulnerable to the long-term effects of treatment for PBT.

Superior Intellectual Outcomes After Proton Radiotherapy Compared With Photon Radiotherapy for Pediatric Medulloblastoma

PURPOSE

Proton radiotherapy (PRT) may lessen the neuropsychological risk traditionally associated with cranial radiotherapy for the treatment of pediatric brain tumors by reducing the dose to normal tissue compared with that of photon radiotherapy (XRT). We examined the change in intellectual scores over time in patients with pediatric medulloblastoma treated with craniospinal PRT versus XRT.

METHODS

Intelligence test scores were obtained for a sample of pediatric patients treated between 2007 and 2018 on the same medulloblastoma protocols that differed only in radiotherapy modality (PRT v XRT). Growth curve analyses compared change in scores over time since diagnosis between groups.

RESULTS

Longitudinal intelligence data from 79 patients (37 PRT, 42 XRT) were examined. Groups were similar on most demographic/clinical variables, including sex (67.1% male), age at diagnosis (mean, 8.6 years), craniospinal irradiation dose (median, 23.4 Gy), length of follow-up (mean, 4.3 years), and parental education (mean, 14.3 years). Boost dose (P < .001) and boost margin (P = .001) differed between groups. Adjusting for covariates, the PRT group exhibited superior long-term outcomes in global intelligence quotient (IQ), perceptual reasoning, and working memory compared with the XRT group (all P < .05). The XRT group exhibited a significant decline in global IQ, working memory, and processing speed (all P < .05). The PRT group exhibited stable scores over time in all domains with the exception of processing speed (P = .003).

CONCLUSION

To our knowledge, this is the first study to compare intellectual trajectories between pediatric patients treated for medulloblastoma with PRT versus those treated with XRT on comparable, contemporary protocols. PRT was associated with more favorable intellectual outcomes in most domains compared with XRT, although processing speed emerged as a vulnerable domain for both groups. This study provides the strongest evidence to date of an intellectual sparing advantage with PRT in the treatment of pediatric medulloblastoma.

Predictors of neuropsychological late effects and white matter correlates in children treated for a brain tumor without radiation therapy

BACKGROUND

Little is known about cognition and predictors of neuropsychological outcomes in pediatric low-grade glioma (PLGG) survivors treated without radiation therapy. This research expands upon our previous work by further identifying the cognitive profile of PLGG patients treated without radiation therapy, investigating the specific medical and demographic variables that predict functioning, and examining white matter structure and its relationship to neuropsychological performance.

PROCEDURE

Nineteen PLGG patients (11-19 years) were administered the Wechsler Intelligence Scale for Children/Wechsler Adult Intelligence Scale, and subtests from the Woodcock-Johnson Tests of Cognition (visual matching, rapid picture naming, and pair cancellation) and Cambridge Neuropsychological Test Automated Battery (pattern recognition memory, delayed matching to sample, intra-extra dimensional set shift, motor screening task, rapid visual information processing, and spatial span).

RESULTS

The sample had normative weaknesses in verbal working memory, brief attention/vigilance, psychomotor speeded output, visual perception and matching, overall cognition, working memory, and processing speed. Increased surgeries or subtotal resections, hydrocephalus, shunting procedures, chemotherapy, NF1, and supratentorial location were predictive of cognitive deficits. Broad white matter involvement of the frontal, temporal, parietal, and occipital lobes as well as the cerebellum, as inferred from diffusion tensor imaging indices of decreased fiber orientation and increased water diffusion, was related to many cognitive difficulties.

CONCLUSIONS

This study comprehensively examines cognitive functioning in PLGG patients treated without radiation therapy, predictors of cognition, and its relation to white matter structure. Our findings indicate that medical and demographic variables other than radiation therapy can lead to cognitive late effects with diffuse white matter involvement.

Neurocognitive evaluation of long term survivors of atypical teratoid rhabdoid tumors (ATRT): The Canadian registry experience

BACKGROUND

Because atypical teratoid rhabdoid tumor(ATRT) is a rare disease of infancy carrying a grim prognosis, focus on long-term outcome, especially neurocognitive remained very limited. With new era of multimodality therapy, an increasing proportion of patients are now long-term survivors.

PROCEDURE

Retrospective review of neuropsychological (NP) status of survivors from the Canadian ATRT registry.

RESULTS

Among 77 patients diagnosed between 1995-2012, 16(22%) were survivors. Formal NP assessments were available in eight patients. Partial information on academic achievement was available on three additional patients. There were four girls and seven boys diagnosed at a median age of 27.5 months. Seven patients underwent complete resection and three had metastatic disease. All but one received sequential high dose chemotherapy. Five patients received intrathecal chemotherapy. Three patients underwent radiation. Median age at time of formal NP assessment was 7.6 years (3.9-9.8). Full Scale Intellectual Quotient (FSIQ) ranged from less than 50-119 (mean 78). Simple expressive and receptive language appeared relatively preserved. Three recently diagnosed patients (median time assessment from diagnosis 2.6 years (1.6-4.7)) had average to high average FSIQ, academic and visual spatial skills, visual, and verbal memory. Five other patients diagnosed earlier and tested at a median time of 4.9 years (3.3-8.3) post-diagnosis had a FSIQ ranging from <50 to 71. Approximately 50% of their scores were in the impaired range.

CONCLUSION

Overall this cohort appears significantly impaired at school age despite the absence of systematic radiotherapy. Larger series focusing on neurocognitive outcome are needed in the current context where treatment strategies include adjuvant radiation.

Visualization and segmentation of reciprocal cerebrocerebellar pathways in the healthy and injured brain

Detailed information regarding the neuroanatomy of reciprocal cerebrocerebellar pathways is based on well-documented animal models. This knowledge has not yet been fully translated to humans, in that the structure of reciprocal cerebrocerebellar pathways connecting the cerebellum with frontal lobe has not been shown in its entirety. We investigated the impact of injury and age on cerebrocerebellar pathway microstructure using diffusion tensor imaging (DTI) and probabilistic tractography. We used medulloblastoma (MB) as an injury model due to the known impact of tumor/treatment on the cerebellum, one of the main nodes of cerebrocerebellar pathways. We delineated and segmented reciprocal cerebrocerebellar pathways connecting the cerebellum with frontal lobe in 38 healthy children (HC) and 34 children treated for MB, and compared pathway segment DTI measures between HC and MB and across three age cohorts: childhood, early adolescence, and late adolescence. Pathway compromise was evident for the MB group compared to HC, particularly within posterior segments (Ps<0.01). Though we found no age effect, group differences in microstructure were driven by pathway segment (posterior) and age cohort (adolescence), which may reflect the extent of injury to the posterior fossa following treatment for MB and age cohort differences in radiation treatment protocol in our sample. We have examined the microstructure of reciprocal cerebrocerebellar connections in the pediatric brain and have found that these pathways are injured in MB, a clinical population treated with surgery, radiation, and chemotherapy. Our findings support the late effects literature describing white matter injury emergence in the years following treatment for MB.

Medulloblastoma subgroup-specific outcomes in irradiated children: who are the true high-risk patients?

BACKGROUND

The advent of integrated genomics has fundamentally changed our understanding of medulloblastoma. Although survival differences exist among the 4 principal subgroups, this has yet to be elucidated in a North American cohort of irradiated patients.

METHODS

Ninety-two consecutive patients between the ages of 3 and 17 treated with surgery, craniospinal irradiation, and chemotherapy were identified at the Hospital for Sick Children. Molecular subgrouping was performed using nanoString.

RESULTS

Two treatment periods were identified: prior to 2006 as per the protocols of the Children's Oncology Group, and after 2006 per the St Jude Medulloblastoma 03 protocol. Five-year progression-free survival (PFS) over the entire cohort was 0.801 (95% CI: 0.692-0.875) with no significant difference between treatment protocols. Strikingly, we found that Group 4 patients had excellent 5-year PFS of 0.959 (95% CI: 0.744-0.994) for average risk and 0.887 (95% CI: 0.727-0.956) across all Group 4 patients. Group 3 patients had 5-year PFS of 0.733 (95% CI: 0.436-0.891). Sonic hedgehog patients did poorly across both treatment protocols, with 5-year PFS of 0.613 (95% CI: 0.333-0.804), likely owing to a high proportion of TP53 mutated patients in this age group.

CONCLUSIONS

In a cohort of irradiated patients over 3 years of age, PFS for Group 4 patients was significantly improved compared with initial reports. The impact of subgroup affiliation in these children needs to be assessed in large prospectively treated cooperative protocols to determine if more than just WNT patients can be safely selected for de-escalation of therapy.

De-escalation of therapy for pediatric medulloblastoma: trade-offs between quality of life and survival

BACKGROUND

Treatment intensity for pediatric medulloblastoma may vary depending on the type of medulloblastoma. In some cases, the dose of radiation may be reduced or eliminated. Correspondingly, there may be trade-offs between quality of life and survival. In this study, focus groups were conducted with parents and clinicians to explore their opinions about these trade-offs as well as the alignment/misalignment between parents and clinicians regarding the trade-offs.

METHODS

One hour semi-structured focus groups were conducted with parents of children with medulloblastoma and health care providers who were involved in the care of these children.

RESULTS

Parents and providers showed differences in which factors they believe have the greatest impact on quality of life for children with medulloblastoma and their families. For parents, the most important factor is social functioning and their child's ability to make friends and have a social life. In contrast, providers thought that parents cared most about their child's cognitive functioning and ability to attend and perform in school.

CONCLUSION

Understanding parents' perspectives on quality of life is important in terms of providing support services that target the areas that the parents prioritize. The types of functioning that are most strongly correlated with quality of life from the parents' perspective may be the ones that should be targeted to protect during treatment. Pediatr Blood Cancer 2014;61:1300-1304. © 2014 Wiley Periodicals, Inc.

Impact of Craniospinal Dose, Boost Volume, and Neurologic Complications on Intellectual Outcome in Patients With Medulloblastoma

Purpose

To examine the impact of radiation (ie, craniospinal irradiation [CSR] dose and boost volume) and complications (ie, hydrocephalus and other neurologic complications, including mutism) on patterns of change in intellectual functioning in medulloblastoma survivors.

Patients and Methods

We conducted a retrospective review of 113 patients treated for medulloblastoma between 1983 and 2011 who were seen for neuropsychological assessment, including longitudinal follow-up of intellectual function. Patients were treated with either standard-dose CSR with a posterior fossa (PF) boost (n = 51), standard-dose CSR plus tumor bed (TB) boost (n = 9), reduced-dose CSR plus PF boost (n = 28), or reduced-dose CSR plus TB boost (n = 23), with or without chemotherapy. A subset of patients developed hydrocephalus that required cerebrospinal fluid (CSF) diversion (n = 54) and/or other neurologic complications (n = 40), more than half of which were postoperative mutism (n = 25). Growth curve analysis was used to determine stability or change in intelligence scores over time.

Results

Patients treated with reduced-dose CSR plus TB boost showed stable intellectual trajectories, whereas patients treated with higher doses and larger boost volumes experienced intellectual declines. Presence of complications was associated with worse intellectual outcome; however, hydrocephalus requiring CSF diversion and mutism differed in their pattern of decline.

Conclusion

These results improve our understanding of factors that impair intellectual outcome in patients treated for medulloblastoma. Lower doses of CSR and smaller boost volumes seem to mitigate intellectual decline. Our findings validate the use of TB boost and suggest PF boost should be reconsidered.