Chemotherapy-induced neurotoxicity in pediatric solid non-CNS tumor patients: An update on current state of research and recommended future directions

Cerebral blood flow and structural connectivity after working memory or physical training in paediatric cancer survivors - Exploratory findings

Paediatric cancer survivors often suffer from cognitive long-term difficulties. Consequently, strengthening cognition is of major clinical relevance. This study investigated cerebral changes in relation to cognition in non-brain tumour paediatric cancer survivors after working memory or physical training compared to a control group. Thirty-four children (≥one-year post-treatment) either underwent eight weeks of working memory training (n = 10), physical training (n = 11), or a waiting period (n = 13). Cognition and MRI, including arterial spin labelling and diffusion tensor imaging, were assessed at three time points (baseline, post-training, and three-month follow-up). Results show lower cerebral blood flow immediately after working memory training (z = -2.073, p = .038) and higher structural connectivity at the three-month follow-up (z = -2.240, p = .025). No cerebral changes occurred after physical training. Short-term changes in cerebral blood flow correlated with short-term changes in cognitive flexibility (r = -.667, p = .049), while long-term changes in structural connectivity correlated with long-term changes in working memory (r = .786, p = .021). Despite the caution given when interpreting data from small samples, this study suggests a link between working memory training and neurophysiological changes. Further research is needed to validate these findings.

Investigation of cognitive functions in children with bone tumours and lymphoma in treatment process

BACKGROUND

Neurocognitive sequelae are among the most debilitating effects of cancer observed in children. Yet we know very little about the impact on neurocognitive functioning, especially cancer types that develop outside the central nervous system. This study aimed to assess and compare the cognitive functions (CoF) of children with bone tumours and lymphoma in the treatment process.

METHODS

The CoF of children with bone tumours (n = 44), lymphoma (n = 42) and their non-cancer peers (n = 55) were assessed with Dynamic Occupational Therapy Assessment for Children. The CoF of children with cancer were compared with their non-cancer peers. Then, children with bone tumours and lymphoma were compared in binary.

RESULTS

One-hundred forty-one children aged 6-12 years with a mean age of 9.4 (SD = 1.5) were included in this study. The orientation and visuomotor construction functions of children with bone tumours and orientation, praxis and visuomotor construction functions of children with lymphoma performed worse than their non-cancer peers (pk  < 0.001). While orientation, spatial perception, visuomotor construction and thinking operations functions of children with bone tumours and lymphoma were similar (pk  > 0.016), praxis functions of children with lymphoma were found to be worse than children with bone tumours (pk  < 0.016).

CONCLUSIONS

Our findings show that children with bone tumours and lymphoma in the process of treatment are at risk for impairment of their CoF. The findings highlight the importance of assessing CoF in children with bone tumours and lymphoma and considering specific differences between groups. It is essential to assess CoF and develop early intervention plans in these children.

Neurocognitive outcomes in adult survivors of neuroblastoma: A report from the Childhood Cancer Survivor Study

BACKGROUND

Despite survival improvements, there is a paucity of data on neurocognitive outcomes in neuroblastoma survivors. This study addresses this literature gap.

METHODS

Neurocognitive impairments in survivors were compared to sibling controls from the Childhood Cancer Survivor Study (CCSS) using the CCSS Neurocognitive Questionnaire. Impaired emotional regulation, organization, task efficiency, and memory defined as scores ≥90th percentile of sibling norms. Modified Poisson regression models evaluated associations with treatment exposures, era of diagnosis, and chronic conditions. Analyses were stratified by age at diagnosis (≤1 and >1 year) as proxy for lower versus higher risk disease.

RESULTS

Survivors (N = 837; median [range] age, 25 [17-58] years, age diagnosed, 1 [0-21] years) were compared to sibling controls (N = 728; age, 32 [16-43] years). Survivors had higher risk of impaired task efficiency (≤1 year relative risk [RR], 1.48; 95% confidence interval [CI], 1.08-2.03; >1 year RR, 1.58; 95% CI, 1.22-2.06) and emotional regulation (≤1 year RR, 1.51; 95% CI, 1.07-2.12; >1 year RR, 1.44; 95% CI, 1.06-1.95). Impaired task efficiency associated with platinum exposure (≤1 year RR, 1.74; 95% CI, 1.01-2.97), hearing loss (≤1 year RR, 1.95; 95% CI, 1.26-3.00; >1 year RR, 1.56; 95% CI, 1.09-2.24), cardiovascular (≤1 year RR, 1.83; 95% CI, 1.15-2.89; >1 year RR, 1.74; 95% CI, 1.12-2.69), neurologic (≤1 year RR, 2.00; 95% CI, 1.32-3.03; >1 year RR, 2.29; 95% CI, 1.64-3.21), and respiratory (>1 year RR, 2.35; 95% CI, 1.60-3.45) conditions. Survivors ≤1 year; female sex (RR, 1.54; 95% CI, 1.02-2.33), cardiovascular (RR, 1.71; 95% CI, 1.08-2.70) and respiratory (RR, 1.99; 95% CI, 1.14-3.49) conditions associated impaired emotional regulation. Survivors were less likely to be employed full-time (p < .0001), graduate college (p = .035), and live independently (p < .0001).

CONCLUSIONS

Neuroblastoma survivors report neurocognitive impairment impacting adult milestones. Identified health conditions and treatment exposures can be targeted to improve outcomes.

PLAIN LANGUAGE SUMMARY

Survival rates continue to improve in patients with neuroblastoma. There is a lack of information regarding neurocognitive outcomes in neuroblastoma survivors; most studies examined survivors of leukemia or brain tumors. In this study, 837 adult survivors of childhood neuroblastoma were compared to siblings from the Childhood Cancer Survivorship Study. Survivors had a 50% higher risk of impairment with attention/processing speed (task efficiency) and emotional reactivity/frustration tolerance (emotional regulation). Survivors were less likely to reach adult milestones such as living independently. Survivors with chronic health conditions are at a higher risk of impairment. Early identification and aggressive management of chronic conditions may help mitigate the level of impairment.

Patient-reported neurocognitive function in adult survivors of childhood and adolescent osteosarcoma and Ewing sarcoma

PURPOSE

Little is known regarding long-term neurocognitive outcomes in osteosarcoma and Ewing sarcoma (EWS) survivors despite potential risk factors. We evaluated associations among treatment exposures, chronic health conditions, and patient-reported neurocognitive outcomes in adult survivors of childhood osteosarcoma and EWS.

METHODS

Five-year survivors of osteosarcoma (N = 604; median age 37.0 years) and EWS (N = 356; median age 35.0 years) diagnosed at < 21 years from 1970 to 1999, and 697 siblings completed the Childhood Cancer Survivor Study Neurocognitive Questionnaire and reported chronic health conditions, education, and employment. Prevalence of reported neurocognitive difficulties were compared between diagnostic groups and siblings. Modified Poisson regression identified factors associated with neurocognitive difficulties.

RESULTS

Osteosarcoma and EWS survivors, vs. siblings, reported higher prevalences of difficulties with task efficiency (15.4% [P = 0.03] and 14.0% [P = 0.04] vs. 9.6%, respectively) and emotional regulation (18.0% [P < 0.0001] and 15.2% [P = 0.03] vs. 11.3%, respectively), adjusted for age, sex, and ethnicity/race. Osteosarcoma survivors reported greater memory difficulties vs. siblings (23.5% vs. 16.4% [P = 0.01]). Comorbid impairment (i.e., ≥ 2 neurocognitive domains) was more prevalent in osteosarcoma (20.0% [P < 0.001]) and EWS survivors (16.3% [P = 0.02]) vs. siblings (10.9%). Neurological conditions were associated with worse task efficiency (RR = 2.17; 95% CI = 1.21-3.88) and emotional regulation (RR = 1.88; 95% CI = 1.01-3.52), and respiratory conditions were associated with worse organization (RR = 2.60; 95% CI = 1.05-6.39) for EWS. Hearing impairment was associated with emotional regulation difficulties for osteosarcoma (RR = 1.98; 95% CI = 1.22-3.20). Patient report of cognitive difficulties was associated with employment but not educational attainment.

CONCLUSIONS

Survivors of childhood osteosarcoma and EWS are at increased risk for reporting neurocognitive difficulties, which are associated with employment status and appear related to chronic health conditions that develop over time.

IMPLICATIONS FOR CANCER SURVIVORS

Early screening, prevention, and treatment of chronic health conditions may improve/prevent long-term neurocognitive outcomes.

Processing efficiency in pediatric cancer survivors: A review and operationalization for outcomes research and clinical utility

OBJECTIVE

Childhood cancer and cancer-related treatments disrupt brain development and maturation, placing survivors at risk for cognitive late effects. Given that assessment tools vary widely across researchers and clinicians, it has been daunting to identify distinct patterns in outcomes across diverse cancer types and to implement systematic neurocognitive screening tools. This review aims to operationalize processing efficiency skill impairment-or inefficient neural processing as measured by working memory and processing speed abilities-as a worthwhile avenue for continued study within the context of childhood cancer.

METHODS

A comprehensive literature review was conducted to examine the existing research on cognitive late effects and biopsychosocial risk factors in order to conceptualize processing efficiency skill trends in childhood cancer survivors.

RESULTS

While a frequently reported pattern of neurobiological (white matter) and cognitive (working memory and processing speed) disruption is consistent with processing efficiency skill impairment, these weaknesses have not yet been fully operationalized in this population. We offer a theoretical model that highlights the impacts of a host of biological and environmental factors on the underlying neurobiological substrates of cancer survivors that precede and may even predict long-term cognitive outcomes and functional abilities following treatment.

CONCLUSION

The unified construct of processing efficiency may be useful in assessing and communicating neurocognitive skills in both outcomes research and clinical practice. Deficits in processing efficiency may serve as a possible indicator of cognitive late effects and functional outcomes due to the unique relationship between processing efficiency skills and neurobiological disruption following cancer treatment. Continued research along these lines is crucial for advancing childhood cancer outcomes research and improving quality of life for survivors.

Cannabinoid drugs against chemotherapy-induced adverse effects: focus on nausea/vomiting, peripheral neuropathy and chemofog in animal models

Although new drugs are being developed for cancer treatment, classical chemotherapeutic agents are still front-line therapies, despite their frequent association with severe side effects that can hamper their use. Cannabinoids may prevent or palliate some of these side effects. The aim of the present study is to review the basic research which has been conducted evaluating the effects of cannabinoid drugs in the treatment of three important side effects induced by classical chemotherapeutic agents: nausea and vomiting, neuropathic pain and cognitive impairment. Several published studies have demonstrated that cannabinoids are useful in preventing and reducing the nausea, vomits and neuropathy induced by different chemotherapy regimens, though other side effects can occur, such as a reduction of gastrointestinal motility, along with psychotropic effects when using centrally-acting cannabinoids. Thus, peripherally-acting cannabinoids and new pharmacological options are being investigated, such as allosteric or biased agonists. Additionally, due to the increase in the survival of cancer patients, there are emerging data that demonstrate an important cognitive deterioration due to chemotherapy, and because the cannabinoid drugs have a neuroprotective effect, they could be useful in preventing chemotherapy-induced cognitive impairment (as demonstrated through studies in other neurological disorders), but this has not yet been tested. Thus, although cannabinoids seem a promising therapeutic approach in the treatment of different side effects induced by chemotherapeutic agents, future research will be necessary to find pharmacological options with a safer profile. Moreover, a new line of research awaits to be opened to elucidate their possible usefulness in preventing cognitive impairment.

Clinical Characteristics and Outcomes of Acute Childhood Encephalopathy in a Tertiary Pediatric Intensive Care Unit

AIM

Childhood encephalopathy comprises a wide range of etiologies with distinctive distribution in different age groups. We reviewed the pattern of encephalopathy admitted to the pediatric intensive care unit (PICU) of a tertiary children's hospital.

METHODS

We reviewed the medical records and reported the etiologies, clinical features, and outcomes of children with encephalopathy.

RESULTS

Twenty-four admissions to the PICU between April 2019 and May 2020 were reviewed. The median (interquartile range) age was 10.0 (14.7) years and 62.5% were boys. Confusion (66.7%) was the most common presentation. Adverse effects related to medications (33.3%) and metabolic disease (20.8%) were predominant causes of encephalopathies in our study cohort. Methotrexate was responsible for most of the medication-associated encephalopathy (37.5%), whereas Leigh syndrome, pyruvate dehydrogenase deficiency and Wernicke's encephalopathy accounted for those with metabolic disease. The median Glasgow Coma Scale (GCS) on admission was 12.5 (9.0). Antimicrobials (95.8%) and antiepileptic drugs (60.9%) were the most frequently given treatment. Children aged 2 years or younger were all boys (P = 0.022) and had a higher proportion of primary metabolic disease (P = 0.04). Intoxication or drug reaction only occurred in older children. The mortality was 8.3%, and over half of the survivors had residual neurological disability upon PICU discharge. Primary metabolic disease (P = 0.002), mechanical ventilation (P = 0.019), failure to regain GCS back to baseline level (P = 0.009), and abnormal cognitive function on admission (P = 0.03) were associated with cerebral function impairment on PICU discharge.

CONCLUSIONS

Primary metabolic encephalopathy was prevalent in younger children, whereas drug-induced toxic encephalopathy was common among older oncology patients. Survivors have significant neurologic morbidity. Failure to regain baseline GCS was a poor prognostic factor for neurological outcomes.

Cannabinoid Drugs-Related Neuroprotection as a Potential Therapeutic Tool Against Chemotherapy-Induced Cognitive Impairment

In recent years, and particularly associated with the increase of cancer patients’ life expectancy, the occurrence of cancer treatment sequelae, including cognitive impairments, has received considerable attention. Chemotherapy-induced cognitive impairments (CICI) can be observed not only during pharmacological treatment of the disease but also long after cessation of this therapy. The lack of effective tools for its diagnosis together with the limited treatments currently available for alleviation of the side-effects induced by chemotherapeutic agents, demonstrates the need of a better understanding of the mechanisms underlying the pathology. This review focuses on the comprehensive appraisal of two main processes associated with the development of CICI: neuroinflammation and oxidative stress, and proposes the endogenous cannabinoid system (ECS) as a new therapeutic target against CICI. The neuroprotective role of the ECS, well described in other cognitive-related neuropathologies, seems to be able to reduce the activation of pro-inflammatory cytokines involved in the neuroinflammatory supraspinal processes underlying CICI. This review also provides evidence supporting the role of cannabinoid-based drugs in the modulation of oxidative stress processes that underpin cognitive impairments, and warrant the investigation of endocannabinoid components, still unknown, that may mediate the molecular mechanism behind this neuroprotective activity. Finally, this review points forward the urgent need of research focused on the understanding of CICI and the investigation of new therapeutic targets.

Brain Microstructural Changes Associated With Neurocognitive Outcome in Intracranial Germ Cell Tumor Survivors

Background

Childhood intracranial germ cell tumor (GCT) survivors are prone to radiotherapy-related neurotoxicity, which can lead to neurocognitive dysfunctions. Diffusion kurtosis imaging (DKI) is a diffusion MRI technique that is sensitive to brain microstructural changes. This study aimed to investigate the association between DKI metrics versus cognitive and functional outcomes of childhood intracranial GCT survivors.

Methods

DKI was performed on childhood intracranial GCT survivors (n = 20) who had received cranial radiotherapy, and age and gender-matched healthy control subjects (n = 14). Neurocognitive assessment was performed using the Hong Kong Wechsler Intelligence Scales, and functional assessment was performed using the Lansky/Karnofsky performance scales (KPS). Survivors and healthy controls were compared using mixed effects model. Multiple regression analyses were performed to determine the effects of microstructural brain changes of the whole brain as well as the association between IQ and Karnofsky scores and the thereof.

Results

The mean Intelligence Quotient (IQ) of GCT survivors was 91.7 (95% CI 84.5 – 98.8), which was below the age-specific normative expected mean IQ (P = 0.013). The mean KPS score of GCT survivors was 85.5, which was significantly lower than that of controls (P < 0.001). Cognitive impairments were significantly associated with the presence of microstructural changes in white and grey matter, whereas functional impairments were mostly associated with microstructural changes in white matter. There were significant correlations between IQ versus the mean diffusivity (MD) and mean kurtosis (MK) of specific white matter regions. The IQ scores were negatively correlated with the MD of extensive grey matter regions.

Conclusion

Our study identified vulnerable brain regions whose microstructural changes in white and grey matter were significantly associated with impaired cognitive and physical functioning in survivors of pediatric intracranial GCT.

Older age is a protective factor for academic achievements irrespective of treatment modalities for posterior fossa brain tumours in children

The treatment of children with posterior fossa brain tumours (PFBT) impacts their long term functional and imaging outcomes. This study aimed to evaluate academic achievement correlated with long-term sequelae after different PFBT treatment modalities. The study cohort consisted of 110 survivors (median age at diagnosis 10.1 years and median time of follow up 13.2 years) who completed hearing questionnaires, neurological assessment and MRI of the brain ≥5 years after the end of treatment. There were three treatment groups. A cisplatin group which underwent cisplatin chemotherapy, radiotherapy and surgery (medulloblastoma N = 40), a radiotherapy group which underwent radiotherapy and surgery (astrocytoma/ependymoma N = 30), and a surgery group (astrocytoma N = 40). Academic achievement was correlated to the age at diagnosis, ototoxicity, Karnofsky score (KS), and MRI findings (Fazekas Score (FS)- treatment related parenchymal changes). For a modelled age at diagnosis of five years, the cisplatin group had lower academic achievements compared to the radiotherapy (p = 0.028) and surgery (p = 0.014) groups. Academic achievements evaluated at a modelled age of 10 years at diagnosis did not significantly differ among the treatment groups. The cisplatin group exhibited a higher occurrence of ototoxicity than the radiotherapy (p<0.019) and surgery groups (p<0.001); however, there was no correlation between ototoxicity and academic achievements (p = 0.722) in older age at diagnosis. The radiotherapy group exhibited lower KS than the surgery group (p<0.001). KS significantly influenced academic achievements in all groups (p<0.000). The cisplatin group exhibited higher FS than the surgery group (p<0.001) while FS did not correlate with academic achievement (p = 0.399). Older age is a protective factor for academic achievements irrespective of a treatment modality.

The impact of cancer and chemotherapy during pregnancy on child neurodevelopment: A multimodal neuroimaging analysis

BACKGROUND

This study applies multimodal MRI to investigate neurodevelopment in nine-year-old children born to cancer-complicated pregnancies.

METHODS

In this cohort study, children born after cancer-complicated pregnancies were recruited alongside 1:1 matched controls regarding age, sex and gestational age at birth (GA). Multimodal MRI was used to investigate whole-brain and subcortical volume, cortical structure (using surface-based morphometry), white matter microstructure (using fixel-based analysis) and functional connectivity (using resting-state blood-oxygen-level-dependant signal correlations). Graph theory probed whole-brain structural and functional organization. For each imaging outcome we conducted two group comparisons: 1) children born after cancer-complicated pregnancies versus matched controls, and 2) the subgroup of children with prenatal chemotherapy exposure versus matched controls. In both models, we used the covariate of GA and the group-by-GA interaction, using false-discovery-rate (FDR) or family-wise-error (FWE) correction for multiple comparisons. Exploratory post-hoc analyses investigated the relation between brain structure/function, neuropsychological outcome and maternal oncological/obstetrical history.

FINDINGS

Forty-two children born after cancer-complicated pregnancies were included in this study, with 30 prenatally exposed to chemotherapy. Brain organization and functional connectivity were not significantly different between groups. Both cancer and chemotherapy in pregnancy, as compared to matched controls, were associated with a lower travel depth, indicating less pronounced gyrification, in the left superior temporal gyrus (pFDR ≤ 006), with post-hoc analysis indicating platinum derivatives during pregnancy as a potential risk factor (p = .028). Both cancer and chemotherapy in pregnancy were related to a lower fibre cross-section (FCS) and lower fibre density and cross-section (FDC) in the posterior corpus callosum and its tapetal fibres, compared to controls. Higher FDC in the chemotherapy subgroup and higher FCS in the whole study group were observed in the anterior thalamic radiations. None of the psycho-behavioural parameters correlated significantly with any of the brain differences in the study group or chemotherapy subgroup.

INTERPRETATION

Prenatal exposure to maternal cancer and its treatment might affect local grey and white matter structure, but not functional connectivity or global organization. While platinum-based therapy was identified as a potential risk factor, this was not the case for chemotherapy in general.

FUNDING

This project has received funding from the European Union's Horizon 2020 research and innovation program (European Research council, grant no 647,047), the Foundation against cancer (Stichting tegen kanker, grant no. 2014-152) and the Research Foundation Flanders (FWO, grants no. 11B9919N, 12ZV420N).

Change of White Matter Integrity in Children With Hematopoietic Stem Cell Transplantation

BACKGROUND

Advances in hematopoietic stem cell transplantation have improved the survival rate of malignant diseases and congenital immunodeficiencies. It has become important to assess long-term complications in survivors. To assess neurological abnormalities in children treated by transplantation, diffusion tensor imaging was performed.

METHODS

Forty children who underwent head diffusion tensor imaging before and after their first transplantation were enrolled. Patients with brain lesions on conventional MRI were excluded. Fractional anisotropy and mean diffusivity were compared between patients and 28 control subjects using tract-based spatial statistics. The Strengths and Difficulties Questionnaire was administered as a behavioral evaluation after transplantation, and diffusion tensor images of patients with and without behavioral abnormalities were compared.

RESULTS

The age of patients and controls was 0 to 19 years and 0 to 16 years, respectively. The date of diffusion tensor imaging was 10 to 57 days before and 40 to 153 days after transplantation. Tract-based spatial statistics showed fractional anisotropy reduction in widespread white matter in patients before and after transplantation. Mean diffusivity was high before transplantation and normalized after transplantation. Analysis comparing before and after hematopoietic stem cell transplantation shows no difference in fractional anisotropy and a higher mean diffusivity before hematopoietic stem cell transplantation. In patients with behavioral abnormalities, low fractional anisotropy and high mean diffusivity remained after transplantation.

CONCLUSIONS

Longitudinal diffusion tensor imaging showed white matter abnormalities in children without conventional MRI abnormalities, which were related to behavioral problems after transplantation. Diffusion tensor imaging is useful for behavioral assessment in children undergoing transplantation.

Prevalence of leukoencephalopathy and its potential cognitive sequelae in cancer patients

Due to the rising use of chemotherapy treatment in cancer patients and growing survival rates, therapy-induced neurotoxic side effects are increasingly reported. Given the ambiguity about the prevalence and severity of leukoencephalopathy, one of such toxic side effects, in non-central nervous system (CNS) cancer patients, we performed a systematic literature search using the PubMed/Medline database to summarize existing literature regarding leukoencephalopathy epidemiology in non-CNS cancer patients and its potential cognitive sequelae. The search was based on the following terms: ('MRI' OR 'T2-weighted MRI' OR 'FLAIR') AND ('cancer' OR 'tumour' OR 'leukaemia' OR 'neoplasms') AND ('chemotherapy' OR 'radiotherapy') AND ('posterior reversible encephalopathy' OR 'leukoencephalopathy' OR 'cerebral ischaemia' OR 'stroke'). Thirty-two studies discussing the occurrence of leukoencephalopathy in cancer patients were included, of which the majority investigated Acute Lymphoblastic Leukaemia (ALL) patients (n = 22).Regularly scanned ALL patients showed a prevalence of leukoencephalopathy between 17 - 87%, and 15 - 83% of patients presented with leukoencephalopathy when only scanned after a CNS event. When diagnosed with posterior reversible encephalopathy syndrome, 100% of patients showed leukoencephalopathy because its diagnosis is based in part on observable lesions. An increased prevalence was observed in ALL patients treated with higher doses of methotrexate (5 g/m² MTX, 42 - 87%) when compared to lower doses (< 5 g/m², 32 - 67%). By contrast, in breast cancer patients, white matter lesions were mainly detected in case of neurological symptoms, but not (yet) clearly associated with chemotherapy administration. However, chemotherapy treatment was associated with more infratentorial microbleeds in breast cancer patients . Up to 50% of other (neurologically asymptomatic) solid tumour patients presented white matter lesions, even years after treatment. When cognitive data were investigated, lesioned patients showed lower scores on neurocognitive tests in 50% of studies, years after ending therapy.In conclusion, leukoencephalopathy is well-documented for ALL patients (with a focus on methotrexate), but there is a lack of knowledge for other intravenous chemotherapeutics, other oncological populations, wider age ranges and possible risk factors (e.g. history of CNS event). Furthermore, the long-term neuropsychological impact and potential risk for neurodegenerative processes due to leukoencephalopathy remains inconclusive. Hence, large international databanks, epidemiological and prospective case-control studies are necessary to stratify risk groups for CNS-related side effects.

Neurodevelopmental Consequences of Pediatric Cancer and Its Treatment: The Role of Sleep

Cognitive impairment is frequent in pediatric cancer, and behavioral and psychological disturbances often also affect children who have survived cancer problems. Furthermore, pediatric tumors are also often associated with sleep disorders. The interrelationship between sleep disorders, neurodevelopmental disorders and pediatric cancer, however, is still largely unexplored. In this narrative review we approach this important aspect by first considering studies on pediatric cancer as a possible cause of neurodevelopmental disorders and then describing pediatric cancer occurring as a comorbid condition in children with neurodevelopmental disorders. Finally, we discuss the role of sleep disorders in children with cancer and neurodevelopmental disorders. Even if the specific literature approaching directly the topic of the role of sleep in the complex relationship between pediatric cancer and neurodevelopmental disorders was found to be scarce, the available evidence supports the idea that in-depth knowledge and correct management of sleep disorders can definitely improve the health and quality of life of children with cancer and of their families.

Neural correlates of working memory function in pediatric cancer survivors treated with chemotherapy: an fMRI study

The goal of this study is to investigate the neural correlates of working memory function associated with chemotherapy in pediatric cancer survivors using event-related functional MRI (fMRI) analysis. Fifteen pediatric cancer survivors treated with chemotherapy and 15 healthy controls were studied. Blood oxygenation level dependent (BOLD) fMRI was acquired. A visual n-back task was used to test working memory function during the fMRI scan. Responses were recorded via an MRI compatible button box for analysis. fMRI scans were analyzed using statistical parametric mapping software. All statistics were corrected for multiple comparisons by false discovery rate, with p < 0.05 as significance. Patients however gave more incorrect responses (p < 0.05), more no responses (p < 0.05), and longer response times (p < 0.05) compared with healthy controls. Correct responses generated significantly lower BOLD responses in the posterior cingulate for pediatric cancer survivors compared with controls (p < 0.05). Incorrect responses generated significantly greater BOLD responses in the angular gyrus in survivors (p < 0.05), and no response trials generated greater BOLD responses within the superior parietal lobule (p < 0.05) compared with controls. Working memory impairment appears to be due to an inability to manipulate information and to retrieve information from memory. The ability to delineate the affected neural circuits associated with chemotherapy-induced cognitive impairment could inform treatment strategies, identify patients at high risk of developing cognitive deficits, and pre-emptively tailor behavioral enrichment to overcome specific cognitive deficits.

Olfactory function as an independent prognostic factor in glioblastoma

OBJECTIVE

To determine the role of olfactory function in patients with glioblastoma multiforme (GBM) as a prognostic clinical measure.

METHODS

In a prospective case-control study, olfactory testing was performed in 73 patients with primary GBM at baseline during first-line treatment and at later follow-ups. An age-matched control cohort consisted of 49 patients with neurologic diseases, excluding those known to affect olfactory function per se. Depending on the olfactory testing score, patients were allotted to a hyposmia group (HG) or normosmia group (NG). MRI analysis was performed to assess whether tumor location affects olfactory pathways.

RESULTS

Patients with GBM had olfactory dysfunction significantly more often compared to the control cohort (p = 0.003). Tumor location could not explain this finding since no relevant difference in MRI-based olfactory pathway involvement was found between HG and NG (p = 0.131). Patients with olfactory dysfunction had significantly worse overall survival (OS) and progression-free survival (PFS) compared to those without dysfunction (median OS 20.9 vs 40.6 months, p = 0.035; median PFS, 9 vs 19 months, p = 0.022). Multivariate analysis in patients without MRI-based involvement of olfactory pathways confirmed olfaction is an independent prognostic factor for OS (hazard ratio [HR] 0.43; p = 0.042) and PFS (HR 0.51; p = 0.049).

CONCLUSION

This pilot study provides the first indication that olfactory dysfunction is frequently observed in GBM and may be associated with worse survival outcome in GBM. However, validation of these results in an independent cohort is needed.

Long-term leukoencephalopathy and neurocognitive functioning in childhood sarcoma patients treated with high-dose intravenous chemotherapy

PURPOSE

Knowledge is limited regarding the prevalence and persistence of chemotherapy-induced leukoencephalopathy in childhood sarcoma patients. This study explored the presence, clinical relevance, and potential risk factors of leukoencephalopathy in childhood bone and soft tissue sarcoma survivors, treated with intravenous chemotherapy.

METHODS

We acquired cross-sectional neurocognitive data in adult survivors (n = 34) (median age at diagnosis [AaD] = 13.32 years, age range = 16-35 years) and healthy age-matched controls (n = 34). Additionally, magnetic resonance imaging included T2-weighted FLAIR (leukoencephalopathy Fazekas rating), multiexponential T2 relaxation (MET2), and multishell diffusion MRI to estimate myelin integrity-related metrics and fluid movement restrictions. Finally, chemotherapy subgroups (methotrexate, alkylating agents, or combination), AaD, and Apoε and MTHFRC677T polymorphisms were explored as potential risk factors for leukoencephalopathy.

RESULTS

At the group level, quality of life, working memory, processing speed, and visual memory were significantly lower in patients compared to controls. Furthermore, long-term leukoencephalopathy was observed in 27.2% of the childhood sarcoma survivors, which was related to attentional processing speed. Lesions were related to diffusion-derived, but not to myelin-sensitive metrics. A significant interaction effect between AaD and chemotherapy group demonstrated more lesions in case of high-dose methotrexate (HD-MTX) (F = 3.434, P = .047). However, patients treated with alkylating agents (without HD-MTX) also showed lesions in younger patients. Genetic predictors were nonsignificant.

CONCLUSION AND IMPLICATION

This study suggests long-term leukoencephalopathy with possibly underlying changes in vasculature, inflammation, or axonal injury, but not necessarily long-term demyelination. Such lesions could affect processing speed, and as such long-term daily life functioning of these patients.

Long-term impact of prenatal exposure to chemotherapy on executive functioning: An ERP study

OBJECTIVE

This study examines the long-term impact of prenatal exposure to chemotherapy on executive functioning and the contribution of late-prematurity to this effect, using event-related potentials.

METHODS

Mothers of the prenatal-exposed children (n = 20) were diagnosed with cancer and received chemotherapeutic treatment during pregnancy. We recruited healthy controls (n = 20) who were matched on a 1:1 ratio regarding prematurity, age and sex. We assessed executive functioning at the age of nine, using two event-related potential paradigms: a Go/Nogo paradigm to investigate processes of response inhibition and conflict monitoring, as well as a Posner paradigm to investigate spatial attention.

RESULTS

Lower potentials were found in prenatal-exposed children compared to controls in the Go/Nogo P3 and Posner positive slow wave. Moreover, prenatal-exposed children responded slower on the Posner paradigm compared to controls (p < .033), with more incorrect responses (p = .023). In the control group, the N2 Go/Nogo wave was more pronounced in children born after a longer gestation.

CONCLUSIONS

This is the first study that demonstrates an effect of prenatal exposure to chemotherapy on the development of executive functioning, not limited to the effect of late-prematurity.

SIGNIFICANCE

This study emphasizes the necessity of a long-term follow-up of prenatal-exposed children to re-inform clinical practice on the costs and benefits of late-premature induction over treatment during pregnancy.

Neurocognitive outcomes in long-term survivors of Wilms tumor: a report from the St. Jude Lifetime Cohort

PURPOSE

To examine prevalence and predictors of neurocognitive outcomes, social attainment, emotional distress, and health-related quality of life (HRQOL) in long-term survivors of pediatric Wilms tumor (WT).

METHODS

One hundred fifty-eight WT survivors (59% female; mean [SD] age 33 [9.1] years; time since diagnosis 29 [9.1] years) and 354 community controls (55.6% female; 35 [10.2] years) completed comprehensive neuropsychological testing and physical examination, including echocardiography/electrocardiography, pulmonary function tests, and endocrine evaluation. Self-report of emotional distress, HRQOL, and social attainment were collected. Impairment was defined in relation to both controls and normative data. Generalized linear models were developed to examine impact of treatment and chronic health conditions on outcomes.

RESULTS

WT survivors performed poorer than norms and controls in 6 of 16 cognitive variables and 1 of 8 HRQOL variables, with scores ranging from - 0.64 (mathematics) to - 0.21 (verbal fluency) standard deviations below expectations. Compared to controls, WT survivors were less likely to graduate college (odds ratio 2.23, 95% confidence interval 1.46-3.41) and had more moderate to severe neurologic conditions (18.4% vs 8.2%, p < 0.001), which were associated with poor memory (β = - 0.90, p < 0.001), attention (β = - 1.02, p < 0.001), and HRQOL general health (β = - 0.80, p = 0.0015). Treatment variables and cardiopulmonary morbidity (higher in survivors) were not associated with outcomes.

CONCLUSIONS

Survivors of WT demonstrate impairment in neurocognitive function and have lower social attainment during adulthood, with poorer neurocognitive function associated with neurologic morbidity.

IMPLICATIONS FOR CANCER SURVIVORS

Survivors of WT should be offered neurocognitive evaluations and rehabilitation. Neurologic conditions should be routinely assessed, and appropriate support offered to reduce risk for functional limitations.

Longitudinal assessment of chemotherapy-induced changes in brain and cognitive functioning: A systematic review

In addition to the burden of a life-threatening diagnosis, cancer patients are struggling with adverse side-effects from cancer treatment. Chemotherapy has been linked to an array of cognitive impairments and alterations in brain structure and function ("chemobrain"). In this review, we summarized the existing evidence that evaluate the changes in cognitive functioning and brain with chemotherapy, as assessed using structural and functional MRI-based techniques in a longitudinal design. This review followed the latest PRISMA guidelines using Embase, Medline, PsychINFO, Scopus, and Web of Science databases with date restrictions from 2012 to 2017. Fourteen research articles met the key inclusion criteria: (i) the studies involved adult cancer patients (mean age ≥ 18); (ii) the use of chemotherapy in the treatment of cancer; (iii) pre-post assessment of behavioral and brain-based outcomes; and (iv) abstracts written in English. Effect sizes of subjective and objective cognitive impairments from the reviewed studies were estimated using Cohen's d or z-scores. We calculated percentage of mean change or effect sizes for main neuroimaging findings when data were available. Strength of the correlations between brain alterations and cognitive changes was obtained using squared correlation coefficients. Small to medium effect sizes were shown? on individual tests of attention, processing speed, verbal memory, and executive control; and medium effect sizes on self-report questionnaires. Neuroimaging data showed reduced grey matter density in cancer patients in frontal, parietal, and temporal regions. Changes in brain function (brain activation and cerebral blood flow) were observed with cancer across functional networks involving (pre)frontal, parietal, occipital, temporal, and cerebellar regions. Data from diffusion-weighted MRI suggested reduced white matter integrity involving the superior longitudinal fasciculus, corpus callosum, forceps major, and corona radiate, and altered structural connectivity across the whole brain network. Finally, we observed moderate-to-strong correlations between worsening cognitive function and morphological changes in frontal brain regions. While MRI is a powerful tool for detection of longitudinal brain changes in the 'chemobrain', the underlying biological mechanisms are still unclear. Continued work in this field will hopefully detect MRI metrics to be used as biomarkers to help guide cognitive treatment at the individual cancer patient level.

Advanced MR diffusion imaging and chemotherapy-related changes in cerebral white matter microstructure of survivors of childhood bone and soft tissue sarcoma?

With the increase of survival rates of pediatric cancer patients, the number of children facing potential cognitive sequelae has grown. Previous adult studies suggest that white matter (WM) microstructural changes may contribute to cognitive impairment. This study aims to investigate WM microstructure in childhood bone and soft tissue sarcoma. Differences in (micro-)structure can be investigated using diffusion MRI (dMRI). The typically used diffusion tensor model (DTI) assumes Gaussian diffusion, and lacks information about fiber populations. In this study, we compare WM structure of childhood bone and soft tissue sarcoma survivors (n = 34) and matched controls (n = 34), combining typical and advanced voxel-based models (DTI and NODDI model, respectively), as well as recently developed fixel-based models (for estimations of intra-voxel differences, apparent fiber density [AFD] and fiber cross-section [FC]). Parameters with significant findings were compared between treatments, and correlated with subscales of the WAIS-IV intelligence test, age at diagnosis, age at assessment and time since diagnosis. We encountered extensive regions showing lower fractional anisotropy, overlapping with both significant NODDI parameters and fixel-based parameters. In contrast to these diffuse differences, the fixel-based measure of AFD was reduced in the cingulum and corpus callosum only. Furthermore, AFD of the corpus callosum was significantly predicted by chemotherapy treatment and correlated positively with time since diagnosis, visual puzzles and similarities task scores. This study suggests altered WM structure of childhood bone and soft tissue sarcoma survivors. We conclude global chemotherapy-related changes, with particular vulnerability of centrally located WM bundles. Finally, such differences could potentially recover after treatment.

The Brainfit study: efficacy of cognitive training and exergaming in pediatric cancer survivors - a randomized controlled trial

BACKGROUND

Cancer survival comes at a price: pediatric cancer survivors bear a high risk for a wide range of cognitive difficulties. Therefore, interventions targeting these difficulties are required. The aim of the present clinical trial is to extend empirical evidence about efficacy of cognitive and physical training in pediatric cancer survivors. It is hypothesized that early cognitive and physical interventions affect the remediation of pediatric cancer survivors in terms of improved executive functions (primary outcome). Additional positive effects of cognitive and physical intervention to other areas such as memory and attention are expected (secondary outcome). Changes in cognitive performance are expected to be associated with structural and functional changes in the brain.

METHODS

Overall, 150 pediatric cancer survivors and 50 matched controls will be included in this trial. The cancer survivors will be randomly assigned to either a computerized cognitive training, a physical training (exergaming) or a waiting control group. They will be assessed with neuropsychological tests, tests of sport motor performance and physical fitness before and after 8 weeks of training and again at a 3-months follow-up. Moreover, neuroimaging will be performed at each of the three time points to investigate the training impact on brain structure and function.

DISCUSSION

With increasing cancer survival rates, evidence-based interventions are of particular importance. New insights into training-related plasticity in the developing brain will further help to develop tailored rehabilitation programs for pediatric cancer survivors.

TRIAL REGISTRATION

KEK BE 196/15; KEK ZH 2015-0397; ICTRP NCT02749877 ; date of registration: 30.11.2016; date of first participant enrolment: .18.01.2017.

Decreased postural control in adult survivors of childhood cancer treated with chemotherapy

The objective of cancer treatment is to secure survival. However, as chemotherapeutic agents can affect the central and peripheral nervous systems, patients must undergo a process of central compensation. We explored the effectiveness of this compensation process by measuring postural behaviour in adult survivors of childhood cancer treated with chemotherapy (CTS). We recruited sixteen adults treated with chemotherapy in childhood for malignant solid (non-CNS) tumours and 25 healthy age-matched controls. Subjects performed posturography with eyes open and closed during quiet and perturbed standing. Repeated balance perturbations through calf vibrations were used to study postural adaptation. Subjects were stratified into two groups (treatment before or from 12 years of age) to determine age at treatment effects. Both quiet (p = 0.040) and perturbed standing (p ≤ 0.009) were significantly poorer in CTS compared to controls, particularly with eyes open and among those treated younger. Moreover, CTS had reduced levels of adaptation compared to controls, both with eyes closed and open. Hence, adults treated with chemotherapy for childhood cancer may suffer late effects of poorer postural control manifested as reduced contribution of vision and as reduced adaptation skills. These findings advocate development of chemotherapeutic agents that cause fewer long-term side effects when used for treating children.