Diffusion tensor imaging and neurocognition in survivors of childhood acute lymphoblastic leukaemia

Genetic Factors and Long-term Treatment-Related Neurocognitive Deficits, Anxiety, and Depression in Childhood Leukemia Survivors: An Exome-Wide Association Study

BACKGROUND

An increased risk of neurocognitive deficits, anxiety, and depression has been reported in childhood cancer survivors.

METHODS

We analyzed associations of neurocognitive deficits, as well as anxiety and depression, with common and rare genetic variants derived from whole-exome sequencing data of acute lymphoblastic leukemia (ALL) survivors from the PETALE cohort. In addition, significant associations were assessed using stratified and multivariable analyses. Next, top-ranking common associations were analyzed in an independent SJLIFE replication cohort of ALL survivors.

RESULTS

Significant associations were identified in the entire discovery cohort (N = 229) between the AK8 gene and changes in neurocognitive function, whereas PTPRZ1, MUC16, TNRC6C-AS1 were associated with anxiety. Following stratification according to sex, the ZNF382 gene was linked to a neurocognitive deficit in males, whereas APOL2 and C6orf165 were associated with anxiety and EXO5 with depression. Following stratification according to prognostic risk groups, the modulatory effect of rare variants on depression was additionally found in the CYP2W1 and PCMTD1 genes. In the replication SJLIFE cohort (N = 688), the male-specific association in the ZNF382 gene was not significant; however, a P value<0.05 was observed when the entire SJLIFE cohort was analyzed. ZNF382 was significant in males in the combined cohorts as shown by meta-analyses as well as the depression-associated gene EXO5.

CONCLUSIONS

Further research is needed to confirm whether the current findings, along with other known risk factors, may be valuable in identifying patients at increased risk of these long-term complications.

IMPACT

Our results suggest that specific genes may be related to increased neuropsychological consequences.

Immune checkpoint inhibitors therapy as the game-changing approach for pediatric lymphoma: A brief landscape

Lymphoma is known as the third most common malignancy in children, and its prevalence and mortality are increasing. Common treatments, including chemotherapy, radiotherapy, and also surgery, despite their efficacy, have many side effects and, have a high chance of disease relapse. Immune Checkpoint Inhibitors (ICIs) offer a promising alternative with potentially fewer risks of relapse and toxicity. This review article aims to investigate the efficacy and safety of ICIs, either as monotherapy or in combination, for pediatric lymphoma patients. ICIs have revolutionized cancer treatment in recent years and have shown remarkable results in several adult cancers. However, their efficacy in treating pediatrics requires further investigation. Nevertheless, some ICIs, including nivolumab, pembrolizumab, and ipilimumab, have demonstrated encouraging outcomes. ICIs therapy is not without risks and can cause side effects, including rash, itching, vitiligo, abdominal pain, diarrhea, dysphagia, epigastric pain, nausea, vomiting, thyroid, and pituitary dysfunction. Overall, this review article highlights the potential benefits and risks of ICIs in treating pediatric lymphoma.

Glymphatic system dysfunction in pediatric acute lymphoblastic leukemia without clinically diagnosed central nervous system infiltration: a novel DTI-ALPS method

BACKGROUND AND OBJECTIVE

Central nervous system (CNS) infiltration commonly occurs in children with acute lymphoblastic leukemia (ALL). Nevertheless, CNS infiltration is rarely detected at the initial diagnosis. The glymphatic system, which regulates cerebrospinal fluid (CSF) and interstitial fluid transport, is considered one of the possible routes of CNS infiltration by leukemia cells. In this study, we used diffusion tensor image analysis along the perivascular space (DTI-ALPS) method to investigate glymphatic system function and obtained CSF volume using synthetic magnetic resonance imaging (SyMRI) in pediatric ALL without clinically diagnosed CNS infiltration.

MATERIALS AND METHODS

Twenty-nine ALL and 29 typically developing (TD) children were prospectively recruited (age 4-16 years) in the present study. Group differences in brain volumetric parameters, brain water diffusivities, and the ALPS index were evaluated after controlling for age, gender, and handedness. Furthermore, significant group-different parameters were correlated with clinical information using partial correlations analysis.

RESULTS

Lower Dxassoc and ALPS index, and increased CSF volume were found in pediatric ALL (all p_{FDR-corrected} < 0.05). Moreover, the ALPS index was negatively associated with the risk classification (r =  - 0.59, p_{FDR-corrected} = 0.04) in pediatric ALL.

CONCLUSIONS

Dysfunction of the glymphatic system and accumulation of CSF were presented in pediatric ALL without clinically diagnosed CNS infiltration. These novel findings suggested that the glymphatic system might be essential in the early-stage process of ALL CNS infiltration, which provides a new direction for exploring underlying mechanisms and early detection of pediatric ALL CNS infiltration.

KEY POINTS

• Lower Dxassoc and ALPS index, and increased CSF volume were found in pediatric ALL (all p_{FDR-corrected} < 0.05). • The ALPS index was negatively associated with the risk classification (r =  -0.59, p_{FDR-corrected} = 0.04) in pediatric ALL. • Dysfunction of the glymphatic system and accumulation of CSF were presented in pediatric ALL without clinically diagnosed CNS infiltration, which suggested that the ALPS index and CSF volume might be promising imaging markers for early detection of pediatric ALL CNS infiltration.

Neurocognitive and radiological changes after cranial radiation therapy in humans and rodents: a systematic review

BACKGROUND

Radiation-induced brain injury is a common long-term side effect for brain cancer survivors, leading to a reduced quality of life. Although there is growing research pertaining to this topic, the relationship between cognitive and radiologically detected lesions of radiation-induced brain injury in humans remains unclear. Furthermore, clinically translatable similarities between rodent models and human findings are also undefined. The objective of this review is to then identify the current evidence of radiation-induced brain injury in humans and to compare these findings to current rodent models of radiation-induced brain injury.

METHODS

This review includes an examination of the current literature on cognitive and radiological characteristics of radiation-induced brain injury in humans and rodents. A thorough search was conducted on PubMed, Web of Science, and Scopus to identify studies that performed cognitive assessments and magnetic resonance imaging techniques on either humans or rodents after cranial radiation therapy. A qualitative synthesis of the data is herein reported.

RESULTS

A total of 153 studies pertaining to cognitively or radiologically detected radiation injury of the brain are included in this systematic review; 106 studies provided data on humans while 47 studies provided data on rodents. Cognitive deficits in humans manifest across multiple domains after brain irradiation. Radiological evidence in humans highlight various neuroimaging-detectable changes post-irradiation. It is unclear, however, whether these findings reflect ground truth or research interests. Additionally, rodent models do not comprehensively reproduce characteristics of cognitive and radiological injury currently identified in humans.

CONCLUSION

This systematic review demonstrates that associations between and within cognitive and radiological radiation-induced brain injuries often rely on the type of assessment. Well-designed studies that evaluate the spectrum of potential injury are required for a precise understanding of not only the clinical significance of radiation-induced brain injury in humans, but also how to replicate injury development in pre-clinical models.

Childhood Acute Lymphoblastic Leukemia Showing Unilateral Motor Dysfunction Prior to Chemotherapy: A Diffusion Tensor Tractography Study

This study aimed to evaluate children with lymphoblastic leukemia and examine the potential correlation between corticospinal tract (CST) injury and motor dysfunction prior to chemotherapy using diffusion tensor tractography (DTT). Nineteen consecutive patients with childhood leukemia (mean age 7.483 ± 3.1 years, range 4-12 years) with unilateral motor dysfunction who underwent DTT prior to chemotherapy and twenty healthy individuals (mean age 7.478 ± 1.2 years; range 4-12 years) were enrolled. Motor functions were evaluated by two independent investigators. The cause of neurological dysfunction was identified based on the CST state using mean fractional anisotropy (FA), mean fiber volume (FV), and CST integrity using DTT. All patients showed disrupted integrity and significantly decreased FA and FV in the affected CST compared to the unaffected CST and the control group (p < 0.05). These DTT results also corresponded to patients' unilateral motor dysfunction. Using DTT, we demonstrated that neurological dysfunction may occur in patients with childhood acute lymphoblastic leukemia even prior to chemotherapy, and that CST injuries correlate with motor dysfunction in these patients. DTT may be a useful modality for evaluating the neural tract state in pediatric leukemia patients with neurological dysfunction.

Risk factors and screening for neurocognitive impacts of therapy

Long-term survivors of pediatric hematologic malignancies are at elevated risk for neurocognitive impairment. Such impairment manifests in different ways at different times during survivorship, with deficits in processing speed, attention, and memory often appearing before deficits in executive function, intelligence, and academics. Survivors exposed to therapies that directly target the central nervous system (CNS), as is the case in acute lymphoblastic leukemia, may demonstrate subtle deficits during frontline therapy, and these deficits may grow and evolve over time. Survivors who do not receive CNS-directed therapies (eg, Hodgkin lymphoma) are also at elevated risk for neurocognitive impairment, although the influence on brain function is indirect through cancer therapy impact on systemic organ function vital to brain health (eg, cardiopulmonary morbidity). Over the course of the survivor's life span, the presence and impact of neurocognitive deficits will be determined by a complex interaction between premorbid development and environment, cancer therapy and clinical care, and posttreatment recovery and health. The timing and type of these treatment and health events will dictate the approach to screening and monitoring for neurocognitive impairment.

Is Brain Network Efficiency Reduced in Young Survivors of Acute Lymphoblastic Leukemia?-Evidence from Individual-Based Morphological Brain Network Analysis

Altered cerebral structure and function have been observed in young survivors of acute lymphoblastic leukemia (ALL). However, the topological organization of the morphological brain networks (MBNs) has not yet been investigated at the individual level. Twenty-three young survivors of ALL and twenty healthy controls (HCs) were recruited and underwent T1-weighted magnetic resonance imaging (MRI) scanning. After preprocessing and segmentation, individual-based MBNs were constructed based on the morphological similarity of gray matter using the combined Euclidean distance. Young survivors showed a significantly lower global clustering coefficient (p = 0.008) and local efficiency (p = 0.035) compared with HCs. In addition, ALL survivors exhibited bidirectional alterations (decreases and increases) in nodal centrality and efficiency around the Rolandic operculum and posterior occipital lobe (p < 0.05, false discovery rate (FDR) corrected). Altered nodal topological efficiencies were associated with off-therapy duration and verbal memory capacity in the digit span test (p < 0.05, FDR corrected). Network-based statistical analysis revealed decreased morphological connections mainly in the pallidum subnetwork, which was negatively correlated with off-therapy durations (p < 0.05). Overall, the topological organization of the individual-based MBNs was disrupted in the young survivors of ALL, which may play a crucial role in executive efficiency deficits.

Disruption of the Corticospinal Tract in Patients with Acute Lymphoblastic Leukemia: A Case Series

Three patients who exhibited hemiplegic symptoms on conventional brain magnetic resonance imaging (MRI), during maintenance treatment for acute lymphoblastic leukemia, are reported. All patients exhibited unilateral motor weakness and poor hand function during chemotherapy. Conventional MRI revealed no definite abnormal lesions. However, in diffusion tensor tractography, the affected corticospinal tract on the contralateral side, consistently with clinical dysfunction, revealed disrupted integrity, decreased fractional anisotropy, and increased apparent diffusion coefficient compared to the results of the unaffected side or control participants. Control participants matched for age, sex, and duration from leukemia diagnosis, who underwent chemotherapy but had no motor impairments, exhibited preserved integrity of both corticospinal tracts. Diffusion tensor tractography can help evaluate patients with acute lymphoblastic leukemia and neurological dysfunction.

Association between fatigue and sleep disturbances during treatment for pediatric acute lymphoblastic leukemia and posttreatment neurocognitive performance

BACKGROUND

Survivors of pediatric acute lymphoblastic leukemia (ALL) are at increased risk of neurocognitive weakness in the areas of attention, executive function, and processing speed. Although fatigue and sleep disturbances are frequent complications of ALL therapy and associated with cognitive functions, the impact of fatigue and sleep profiles during active ALL treatment on posttreatment neurocognitive performance has received limited attention.

METHODS

Pediatric patients (n = 120) with ALL (diagnosed 2011-2016) who completed fatigue and sleep questionnaires at four time points during active treatment were enrolled in a study of neurocognitive performance. Latent class growth analysis identified subgroups of patients with similar sleep and fatigue profiles during treatment. Neurocognitive performance collected >6 months post treatment on 40 participants was compared between latent classes using multivariable linear regression models.

RESULTS

Participants (57.5% male and 79.1% Hispanic or non-Hispanic White) were classified into one of two fatigue and sleep profiles: Class 1 characterized by mild fatigue and sleep disturbances during treatment (50.8%), and Class 2 characterized by higher levels of fatigue and sleep disturbances (49.2%). Posttreatment cognitive performance was in the normal range for most measures, but significantly below normative means for executive function, verbal short-term memory, attention, and distractability measures. Compared to Class 1, Class 2 demonstrated significantly (p < .05) poorer posttreatment neurocognitive performance, particularly in measures of attention.

CONCLUSIONS

Our findings indicate that fatigue and sleep disturbances during the first year of pediatric ALL therapy may impact long-term neurocognitive performance. Sleep and fatigue may be targets for intervention to preserve cognitive functioning in survivors.

Diffusion tensor imaging indices as biomarkers for cognitive changes following paediatric radiotherapy: a systematic review and meta-analysis

Diffusion tensor imaging (DTI) can detect subtle manifestations of white matter (WM) injury following paediatric radiotherapy, which may be a potential biomarker for cognitive changes. This study aimed to synthesise the relationships between DTI indices and cognitive changes following paediatric radiotherapy through systematic review and meta-analysis. PubMed and Scopus electronic databases were used to identify eligible studies. Quality assessment was performed using the National Institute of Health (NIH) Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Information on demographics, DTI changes, and associations to cognitive outcomes were extracted. Meta-analyses were performed on DTI changes in specific anatomical locations. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed in the preparation of this report. Eighteen studies were included (median study size: 21; range 18-146). 17/18 studies showed significant cognitive decline following irradiation. Meta-analyses found significant cognitive changes within patient's group of acute lymphoblastic leukaemia (ALL; standard mean differences [SMD] = -0.075, P = 0.01) and brain tumours (BT; SMD = -1.037, P ≤ 0.001) compared to control/baseline. Both groups also had significantly lower fractional anisotropy (FA) scores in the corpus callosum (ALL: SMD = -0.979, P = 0.002; BT: SMD = -1.025, P < 0.001). Decreased FA was consistently associated with cognitive decline. Correlation on WMFA integrity to cognitive domains was statistically significant (Z = 9.86, P < 0.001) with a large effect size (r = 0.52). White matter tract integrity of the corpus callosum measured with FA has the potential to be a biomarker for radiotherapy-related cognitive decline. Inclusion of DTI in follow-up imaging should be encouraged.

Mouse model of radiation-induced premature ovarian insufficiency reveals compromised oocyte quality: implications for fertility preservation

RESEARCH QUESTION

What is the impact of radiation exposure on oocyte quality and female fertility?

DESIGN

Prepubertal mice underwent whole-body irradiation with a single dose (0.02, 0.1, 0.5, 2, 8 Gy) of gamma- or X-rays. Oocytes were quantified in irradiated (n = 36) and sham-treated (n = 8) mice. After a single exposure to 2 Gy, formation of DNA double-strand breaks (n = 10), activation of checkpoint kinase (Chk2) (n = 10) and dynamics of follicular growth (n = 18) were analysed. Fertility assessment was performed in adult irradiated mice and controls from the number of pups per mouse (n = 28) and the fetal abortion rate (n = 24). Ploidy of mature oocytes (n = 20) was analysed after CREST immunostaining, and uterine sections were examined.

RESULTS

Radiation exposure induced a massive loss of primordial follicles with LD₅₀ below 50 mGy for both gamma and X-rays. Growing follicles survived doses up to 8 Gy. This difference in radiosensitivity was not due to a different amount of radio-induced DNA damage, and Chk2 was activated in all oocytes. Exposure to a 2 Gy dose abolished the long-term fertility of females due to depletion of the ovarian reserve. Detailed analysis indicates that surviving oocytes were able to complete folliculogenesis and could be fertilized. This transient fertility allowed irradiated females to produce a single litter albeit with a high rate of fetal abortion (23%, P = 0.0096), related to altered ploidy in the surviving oocytes (25.5%, P = 0.0035).

CONCLUSIONS

The effects of radiation on surviving oocyte quality question natural conception as a first-line approach in cancer survivors. Together, the data emphasize the need for fertility preservation before radiation exposure and call for reassessment of the use of cryopreserved oocytes.

Structural and Functional Brain Imaging in Long-Term Survivors of Childhood Acute Lymphoblastic Leukemia Treated With Chemotherapy: A Systematic Review

Background

The effect of chemotherapy on brain development in long-term survivors of pediatric acute lymphoblastic leukemia (ALL) was systematically reviewed.

Methods

A systematic search of Pubmed, Scopus, and PsycINFO databases was conducted to identify articles published between January 2000 and February 2020 that implemented magnetic resonance imaging to assess brain structure and function in pediatric ALL survivors (diagnosed younger than 21 years of age). The review included articles that were published on children diagnosed with ALL between 0 and 21 years of age and treated with chemotherapy-only protocols. Articles meeting the inclusion criteria described survivors on average of 5 years or more from diagnosis and were peer-reviewed articles and original studies.

Results

The search yielded 1975 articles with 23 articles meeting inclusion criteria. The review revealed that survivors had statistically significant alterations in brain anatomy, most commonly a smaller hippocampus and impaired microstructural white matter integrity in frontal brain regions. Survivors also had impaired brain function including lower brain network efficiency and altered resting state connectivity. Survivors also displayed widespread reductions in brain activation (ie, frontal, temporal, parietal brain regions) during cognitive tasks.

Conclusion

Although the neurotoxic effects of cancer treatment are reduced in the absence of cranial radiation, survivors treated on chemotherapy-only protocols still display long-term alterations in brain structure and function, which contribute to lifelong neurocognitive late effects.

Effects of Age on White Matter Microstructure in Children With Neurofibromatosis Type 1

Children with neurofibromatosis type 1 (NF1) often report cognitive challenges, though the etiology of such remains an area of active investigation. With the advent of treatments that may affect white matter microstructure, understanding the effects of age on white matter aberrancies in NF1 becomes crucial in determining the timing of such therapeutic interventions. A cross-sectional study was performed with diffusion tensor imaging from 18 NF1 children and 26 age-matched controls. Fractional anisotropy was determined by region of interest analyses for both groups over the corpus callosum, cingulate, and bilateral frontal and temporal white matter regions. Two-way analyses of variance were done with both ages combined and age-stratified into early childhood, middle childhood, and adolescence. Significant differences in fractional anisotropy between NF1 and controls were seen in the corpus callosum and frontal white matter regions when ages were combined. When stratified by age, we found that this difference was largely driven by the early childhood (1-5.9 years) and middle childhood (6-11.9 years) age groups, whereas no significant differences were appreciable in the adolescence age group (12-18 years). This study demonstrates age-related effects on white matter microstructure disorganization in NF1, suggesting that the appropriate timing of therapeutic intervention may be in early childhood.

Immune Checkpoint Inhibitors in Special Populations

Cancer is the second leading cause of death in the worldwide. With the growing burden of cancer, the studies on early diagnosis, treatment and prevention of cancer are rapidly increasing. Recently, many new therapeutic strategies have been discovered, among which immunotherapy has dramatically changed the outlook for cancer treatment. Several clinical trials are underway around the world to produce potential treatments. However, these trials set certain strict joining conditions, so that the clinical data cannot be fully applied in the real world. To help clinical oncologists with treatment decision-making, this review collected recent studies on special populations receiving immunotherapy, including organ transplant patients, pregnant women, pediatric patients, patients with pulmonary tuberculosis, patients with human immunodeficiency virus, and patients with autoimmune diseases and mental illness.

Oxidative Stress in Cerebrospinal Fluid During Treatment in Childhood Acute Lymphoblastic Leukemia

Introduction

Central nervous system (CNS) treatment using intrathecal chemotherapy and cranial radiation to enable long-term disease-free survival from childhood acute lymphoblastic leukemia (ALL) comes at the cost of neurotoxic side effects and long-term sequelae. We investigated oxidative stress as a possible mechanism of chemotherapy-induced neurotoxicity in children with ALL.

Materials and methods

In this case-control study, we estimated the cerebrospinal fluid (CSF) levels of 8-hydroxy-deoxyguanosine (8-OH-dG), a DNA damage product, in children with B-cell ALL and control children. CSF samples were collected at diagnosis, at end of Induction 1, Induction 2, and Induction 2A - consolidation phase. CSF 8-OH-dG levels were compared in children with and without neurotoxicity.

Results

Children with ALL (n=23) at diagnosis had significantly higher median (interquartile range, IQR) CSF 8-OH-dG levels (ng/mL) compared to controls (n=19) [1.97 (1.59-2.56) Vs 0.65 (0.59-0.82), P<0.001]. CSF 8-OH-dG levels at the end of four weeks, eight weeks, and 16 weeks of chemotherapy were [3.96 (2.85-5.44) ng/mL], 1.00 (0.89-1.09), and 3.73 (2.80-4.39) ng/mL, respectively. Out of 23 children with ALL, 12 developed neurotoxicity; the CSF levels of 8-OH-dG in them were only marginally higher compared to those who did not develop neurotoxicity. The CSF 8-OH-dG levels did not show a significant correlation with the number of doses of methotrexate or vincristine received.

Conclusion

Chemotherapy increases the CNS oxidative stress as measured by CSF 8-OH-dG levels, with the levels being proportional to the intensity of chemotherapy. Children with neurotoxicity had only marginally higher CSF 8-OH-dG levels as compared to children without neurotoxicity.

Linguistic-Cognitive Outcomes in Children with Acute Lymphoid Leukemia: An Exploratory Study

Background

Acute lymphoid leukemia (ALL) is the most prevalent cancer of childhood. Impairment in linguistic and memory skills is a possible late sequela in cancer survivors that can limit their quality of life and the overall performance of the individual in society. There is evidence that survivors of ALL treated exclusively with chemotherapy demonstrate significant differences in long-term linguistic and memory functions and also changes in neuroanatomical integrity. However, most studies described do not count on a speech-language pathologist in their team, which we consider important to discuss. Thus, the objective of the present study was to assess memory and vocabulary skills in the pediatric population diagnosed with acute lymphoid leukemia during chemotherapy treatment.

Materials and Methods

An observational cohort study was conducted over a 1.8-year period. Participants of this research were children diagnosed with ALL. All participants were assessed on their linguistic-cognitive skills (ie, vocabulary, short-term memory and lexical access). All data underwent statistical analyses.

Results

The results of the current study found no major significant difference in the linguistic-cognitive performance of children with ALL and their healthy controls. Regarding the linguistic variables, we believe that there should be a differentiation between the effects of the drugs and the effects of social communication skills on performance.

Conclusion

This first characterization of the linguistic-cognitive abilities of children with ALL did not identify differences between these children and their healthy peers, although we were able to identify variables regarding the multidisciplinary team and social communication that should be considered in future studies.

Age- and Intravenous Methotrexate-Associated Leukoencephalopathy and Its Neurological Impact in Pediatric Patients with Lymphoblastic Leukemia

Simple Summary

In this study, we investigated standardized post-chemotherapy magnetic resonance (MR) scans for leukoencephalopathy and patient- and treatment-related risk factors in childhood leukemia patients. As prevalence numbers are limited, our study provides the required estimations for this population. Furthermore, we demonstrate that younger patients might be more at-risk for development of leukoencephalopathy (LE), and that a higher intravenous methotrexate (IV-MTX) dose has a cumulative toxic effect, while the number of intrathecal administrations was not significantly associated with the extent of LE. This can suggest we should modify chemotherapeutic treatment regimens by decreasing the number of IV-MTX applications, with special attention for younger patients.

Abstract

Methotrexate (MTX) is associated with leukoencephalopathy (LE) in children treated for lymphoblastic leukemia/lymphoma (ALL/LBL). However, large-scale studies with systematic MR acquisition and quantitative volumetric lesion information remain limited. Hence, the prevalence of lesion burdens and the potential risk factors of LE in this population are still inconclusive. FLAIR-MRI scans were acquired at the end of treatment in children who were treated for ALL/LBL, which were quantitatively analyzed for LE. Voxels were assigned to the lesion segmentation if indicated by two raters. Logistic and linear regression models were used to test whether lesion presence and size were predicted by risk factors such as age at diagnosis, gender, intrathecal (IT-) or intravenous (IV-)MTX dose, CNS invasion, and acute neurological events. Patients with a pre-existing neurological condition or low-quality MR scan were excluded from the analyses. Of the 129 patients, ten (8%) suffered from CNS invasion. Chemotherapy-associated neurological events were observed in 13 patients (10%) during therapy, and 68 patients (53%) showed LE post-treatment. LE was more frequent in cases of lower age and higher cumulative IV-MTX doses, while the extent of LE and neurological symptoms were associated only with IV-MTX doses. Neurological events were not significantly associated with LE, even though symptomatic patients demonstrated a higher ratio of LE (n = 9/13) than asymptomatic patients (n = 59/116). This study suggests leukoencephalopathy frequently occurs in both symptomatic and asymptomatic leukemia patients. Younger children and patients treated with higher cumulative IV-MTX doses might need more regular screening for early detection and follow-up of associated sequelae.

Cerebrospinal Fluid Biomarkers in Childhood Leukemias

Involvement of the central nervous system (CNS) in childhood leukemias remains a major cause of treatment failures. Analysis of the cerebrospinal fluid constitutes the most important diagnostic pillar in the detection of CNS leukemia and relies primarily on cytological and flow-cytometry studies. With increasing survival rates, it has become clear that treatments for pediatric leukemias pose a toll on the developing brain, as they may cause acute toxicities and persistent neurocognitive deficits. Preclinical research has demonstrated that established and newer therapies can injure and even destroy neuronal and glial cells in the brain. Both passive and active cell death forms can result from DNA damage, oxidative stress, cytokine release, and acceleration of cell aging. In addition, chemotherapy agents may impair neurogenesis as well as the function, formation, and plasticity of synapses. Clinical studies show that neurocognitive toxicity of chemotherapy is greatest in younger children. This raises concerns that, in addition to injury, chemotherapy may also disrupt crucial developmental events resulting in impairment of the formation and efficiency of neuronal networks. This review presents an overview of studies demonstrating that cerebrospinal fluid biomarkers can be utilized in tracing both CNS disease and neurotoxicity of administered treatments in childhood leukemias.

Regional Responses in Radiation-Induced Normal Tissue Damage

Normal tissue side effects remain a major concern in radiotherapy. The improved precision of radiation dose delivery of recent technological developments in radiotherapy has the potential to reduce the radiation dose to organ regions that contribute the most to the development of side effects. This review discusses the contribution of regional variation in radiation responses in several organs. In the brain, various regions were found to contribute to radiation-induced neurocognitive dysfunction. In the parotid gland, the region containing the major ducts was found to be critical in hyposalivation. The heart and lung were each found to exhibit regional responses while also mutually affecting each other's response to radiation. Sub-structures critical for the development of side effects were identified in the pancreas and bladder. The presence of these regional responses is based on a non-uniform distribution of target cells or sub-structures critical for organ function. These characteristics are common to most organs in the body and we therefore hypothesize that regional responses in radiation-induced normal tissue damage may be a shared occurrence. Further investigations will offer new opportunities to reduce normal tissue side effects of radiotherapy using modern and high-precision technologies.

Impact of non-CNS childhood cancer on resting-state connectivity and its association with cognition

INTRODUCTION

Non-central nervous system cancer in childhood (non-CNS CC) and its treatments pose a major threat to brain development, with implications for functional networks. Structural and functional alterations might underlie the cognitive late-effects identified in survivors of non-CNS CC. The present study evaluated resting-state functional networks and their associations with cognition in a mixed sample of non-CNS CC survivors (i.e., leukemia, lymphoma, and other non-CNS solid tumors).

METHODS

Forty-three patients (off-therapy for at least 1 year and aged 7-16 years) were compared with 43 healthy controls matched for age and sex. High-resolution T1-weighted structural magnetic resonance and resting-state functional magnetic resonance imaging were acquired. Executive functions, attention, processing speed, and memory were assessed outside the scanner.

RESULTS

Cognitive performance was within the normal range for both groups; however, patients after CNS-directed therapy showed lower executive functions than controls. Seed-based connectivity analyses revealed that patients exhibited stronger functional connectivity between fronto- and temporo-parietal pathways and weaker connectivity between parietal-cerebellar and temporal-occipital pathways in the right hemisphere than controls. Functional hyperconnectivity was related to weaker memory performance in the patients' group.

CONCLUSION

These data suggest that even in the absence of brain tumors, non-CNS CC and its treatment can lead to persistent cerebral alterations in resting-state network connectivity.

Neurocognitive impairment in Asian childhood cancer survivors: a systematic review

Childhood cancer survivors are at higher risk of developing neurocognitive deficits due to the intensive treatment they received at an early age. Most studies on childhood cancer survivorship have so far focused on the Western populations. Due to the ethnic, genetic, environmental, and cultural differences, clinical data of the Western populations may not be representative of Asian countries. This scoping review systematically summarized the existing clinical evidence of the neurocognitive impairment of Asian childhood cancer survivors. We searched the Embase and Medline databases for studies assessing the neurocognitive functions of survivors in Asia, who were diagnosed with cancer before the age of 19 and completed active treatment. The literature search identified 13 studies involving 2212 participants from five Asian countries: South Korea (n = 4, 30.8%), Taiwan (n = 3, 23.1%), Japan (n = 3, 23.1%), Hong Kong (n = 2, 15.4%), and Thailand (n = 1, 7.7%). The included studies focused on CNS tumors (n = 10, 76.9%), hematological malignancies (n = 7, 53.8%), or heterogeneous cancer diagnoses (n = 3, 23.1%). Collectively, mild-to-moderate impairment in intelligence was observed in 10.0 to 42.8% of survivors, which seemed higher than the reported rate in Western survivors. We speculate that the ethnic and genetic variations in drug responses and susceptibility to adverse chronic toxicities may have contributed to the differences in the prevalence and severity of neurocognitive impairment between these two populations. To better understand the effects of culturally relevant and region-specific environmental risk factors on the post-treatment neurocognitive development in cancer survivors, a holistic approach that addresses the complex interactions between biological, physical, and psychosocial factors is needed. This will aid the development of effective intervention strategies to improve the functional and psychosocial outcomes of cancer survivors in Asian societies.

Quantitative MRI outcomes in child and adolescent leukemia survivors: Evidence for global alterations in gray and white matter

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Studies of cognition in ALL survivors consistently show evidence of mild neurocognitive difficulties.

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Structural MRI showed widespread differences between survivors and controls.

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Gray and white matter volumes were respectively 5 and 6% smaller in survivors.

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Survivors also exhibited altered white matter diffusion overall.

Introduction

Cure rates for pediatric acute lymphoblastic leukemia (ALL) have reached an all-time high (>90%); however, neurocognitive difficulties continue to affect quality of life in at least a subset of survivors. There are relatively few quantitative neuroimaging studies in child and adolescent ALL survivors treated with chemotherapy only. Use of different outcome measures or limited sample sizes restrict our ability to make inferences about patterns of brain development following chemotherapy treatment. In this study, we used magnetic resonance imaging (MRI) to evaluate brain outcomes in ALL survivors, comparing against a group of typically developing, cancer free peers.

Materials and methods

Participants included 71 ALL survivors, on average 8 years after diagnosis and 8–18 years of age, and 83 typically developing controls. Anatomical MRI was performed to evaluate brain structure; diffusion and magnetization transfer MRI were used to examine brain tissue microstructure.

Results

Successful MRI scans were acquired in 67 survivors (94%) and 82 controls (99%). Structurally, ALL survivors exhibited widespread reductions in brain volume, with 6% less white matter and 5% less gray matter than controls (p = 0.003 and 0.0006 respectively). Much of the brain appeared affected – 71 of 90 evaluated structures showed smaller volume – with the most notable exception being the occipital lobe, where no significant differences were observed. Average full-scale IQ in the survivor and control groups were 95 (CI 92–99) and 110 (CI 107–113), respectively. Using data from the NIH Pediatric MRI Data Repository, we evaluated the extent to which elevated IQ in the control group might affect the structural differences observed. We estimated that two thirds of the observed brain differences were attributable to ALL and its treatment. In addition to the structural changes, survivors showed, on average, globally lower white matter fractional anisotropy (-3%) and higher radial diffusivity (+5%) (p < 10⁻⁶), but no differences in magnetization transfer ratio.

Conclusions

Neuroanatomical alterations in late childhood and adolescent ALL survivors treated with chemotherapy-only protocols are widespread, with white matter being somewhat more affected than gray matter. These MRI results indicate brain development is altered in ALL survivors and highlight the need to examine how these alterations emerge.

Altered Functional Connectivity Density in Young Survivors of Acute Lymphoblastic Leukemia Using Resting-State fMRI

Objective

Using functional connectivity density (FCD) mapping measured by resting-state functional magnetic resonance imaging (rs-fMRI), an ultrafast data-driven graph theory approach, we attempted to study the abnormalities in neural activity of young survivors of acute lymphoblastic leukemia (ALL) and to explore the neuropathological evidence of chemotherapy-related cognitive impairment of patients.

Methods

Twenty young survivors of ALL and 18 well-matched healthy controls (HCs) were recruited in this study. All ALL patients and healthy controls underwent rs-fMRI scans and completed neurocognitive testing. The between-group differences in short-range and long-range FCD were calculated by the option of degree centrality (DC) in MATLAB software after preprocessing. The correlations between the FCD value and each of the neurocognitive outcomes were analyzed in the ALL patients.

Results

The group-averaged FCD maps showed similar spatial patterns between the two groups. Compared with the HCs, ALL patients showed decreased long-range FCD in regions of the bilateral lingual gyrus, cingulate cortex, hippocampal gyrus, and right calcarine fissure. Simultaneously, decreased regions in the short-range FCD map were the bilateral lingual gyrus, cingulate cortex, parahippocampal gyrus and right calcarine fissure. Increased functional connectivity (FC) was observed between the region with decreased long-range FCD and the posterior cerebellar lobe, and decreased FC was observed between the region and the middle occipital gyrus, cuneus and lingual gyrus. Thus, there existed no brain areas with increased FCD. The decreased short-range FCD value of ALL patients was positively correlated with the score on the Digit Span Test (Forward), and the increased FC value was negatively correlated with the score on the Trail Making Test part A.

Conclusion

Our results suggest the altered functional connectivity of young survivors of ALL in the posterior region of the brain and posterior lobe of the cerebellum. Alterations in spontaneous neuronal activity seem to parallel the neurocognitive testing, which indicates that the rs-fMRI could be used as a neuroimaging marker for neurological impairment in ALL patients.

Assessment of Executive Functions after Treatment of Childhood Acute Lymphoid Leukemia: a Systematic Review

Individuals treated for childhood acute lymphoblastic leukemia (ALL) have a high survival rate. This fact, however, may lead to neurocognitive impairments in survivors, as shown in some studies. The prefrontal cortex and executive functions seem to be particularly vulnerable due to the late maturation in the development process. Executive impairments have been associated with poorer quality of life in childhood cancer survivors. A systematic review was carried out with studies that assessed executive functions in childhood ALL survivors.\ Studies were collected from five electronic databases: MEDLINE (PubMed); PsycInfo; WebOfScience; LILACS and IBECS. Eighty-four studies were retrieved from the database search, of which 50 were read in full and 26 met the inclusion criteria. The studies were heterogeneous as to the instruments used to assess executive function, the skills assessed and the comparison methods. Despite some discrepancies, ALL survivors seem to exhibit poorer executive functioning than typical controls, but this result did not hold true when subjects were compared to normative mean. Changes in brain structure and dynamics resulting from the disease itself, the toxicity of the treatment and difficulties in coping with the stress during treatment may be related to executive impairments in ALL survivors. Discussion proposed standardized methods and measures for assessing executive functioning in children during and after ALL treatment.

Anatomical brain MRI study of pediatric cancer survivors treated with chemotherapy: Correlation with behavioral measures

The negative impacts of chemotherapy on pediatric patients treated with chemotherapy during the formative years of brain development are understudied compared to adult chemotherapy cancer patients. This work investigated the morphometry, cortical thickness, and subcortical volumes using MRI and their correlations with behavioral measures in pediatric oncology survivors treated with chemotherapy. Chemotherapy-treated childhood cancer survivors (N = 15, 15.12 ± 5.98 years old) diagnosed with a non-central nervous system malignancy and healthy age-matched controls (N = 15, 15.13 ± 4.21 years old) were studied. MRI was acquired at 3 Tesla. Behavioral Rating Inventory of Executive Functioning (BRIEF) Parental Rating, Purdue Pegboard manual dexterity and n-back working memory measures were administered. Structural MRI scans at 3 Tesla were acquired. Voxel-based morphometry, cortical thickness and subcortical volumes were analyzed and correlated with behavioral scores. Parametric statistics with a p < .05 and adjusted for multiple comparison corrections were performed. Patients exhibited significantly smaller gray-matter volumes in the left globus pallidum, bilateral thalami, left caudate and left nucleus accumbens (p < .05) and thinner cortex in the right parahippocampal gyrus (p < .05) compared to controls. BRIEF scores were similar to normative values. Purdue Pegboard revealed manual dexterity deficits compared to normative values, and the n-back task showed working-memory deficits in patients compared to controls. Left thalamus volume positively correlated with dexterity performance (p = .029). The number of correct answers positively correlated and the number of incorrect answers negatively correlated with total-brain and white-matter volume (p < .05), but not gray-matter volume (p > .05). Our results support the hypothesis that the neurotoxicity of systemic chemotherapy has widespread negative effects on brain development in pediatric oncology patients with relatively mild cognitive deficits. MRI identified neuroanatomical changes have the potential to provide neural correlates of the sequelae associated with pediatric chemotherapy.

Auditory attention late effects in pediatric acute lymphoblastic leukemia

This study sought to characterize auditory attention functioning among pediatric Acute Lymphoblastic Leukemia (ALL) survivors treated on a chemotherapy-only protocol, given previous literature suggesting late impact on sustained visual attention. We hypothesized similar deficits would be observed in auditory attention relative to previous literature indicating weakness with aspect of visual attention in this population. Survivors (n = 107, 53 females, M = 12.80 years) completed the Conners Continuous Auditory Test of Attention (CATA). Parents completed the Behavior Assessment System for Children, Second Edition and reported educational performance and services via structured questionnaire. Results indicated several CATA indices associated with sustained auditory attention were significantly worse than normative data, though group means were average. Reflecting individual variability in performance, 50% of the sample performed worse than one standard deviation from the mean on at least one CATA variable. Parent report of attention did not differ from normative means for the sample. Parent-report data indicated that 60% of the sample utilized academic support services, with a large proportion of survivors having utilized special education services. Poorer performance with sustained auditory attention was associated with poor academic outcomes. Greater methotrexate exposure and younger age at diagnosis were risk factors for inattentiveness. No gender differences were identified on direct assessment of auditory attention or parent report of attention, though male gender was associated with poorer educational performance. Findings suggest that auditory attention is an at-risk cognitive domain following treatment for pediatric ALL, and that an association exists between auditory attention and school performance in this population.

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.

Brain Activity Associated With Attention Deficits Following Chemotherapy for Childhood Acute Lymphoblastic Leukemia

BACKGROUND

The impact of contemporary chemotherapy treatment for childhood acute lymphoblastic leukemia on central nervous system activity is not fully appreciated.

METHODS

Neurocognitive testing and functional magnetic resonance imaging (fMRI) were obtained in 165 survivors five or more years postdiagnosis (average age = 14.4 years, 7.7 years from diagnosis, 51.5% males). Chemotherapy exposure was measured as serum concentration of methotrexate following high-dose intravenous injection. Neurocognitive testing included measures of attention and executive function. fMRI was obtained during completion of two tasks, the continuous performance task (CPT) and the attention network task (ANT). Image analysis was performed using Statistical Parametric Mapping software, with contrasts targeting sustained attention, alerting, orienting, and conflict. All statistical tests were two-sided.

RESULTS

Compared with population norms, survivors demonstrated impairment on number-letter switching (P < .001, a measure of cognitive flexibility), which was associated with treatment intensity (P = .048). Task performance during fMRI was associated with neurocognitive dysfunction across multiple tasks. Regional brain activation was lower in survivors diagnosed at younger ages for the CPT (bilateral parietal and temporal lobes) and the ANT (left parietal and right hippocampus). With higher serum methotrexate exposure, CPT activation decreased in the right temporal and bilateral frontal and parietal lobes, but ANT alerting activation increased in the ventral frontal, insula, caudate, and anterior cingulate.

CONCLUSIONS

Brain activation during attention and executive function tasks was associated with serum methotrexate exposure and age at diagnosis. These findings provide evidence for compromised and compensatory changes in regional brain function that may help clarify the neural substrates of cognitive deficits in acute lymphoblastic leukemia survivors.

Gray Matter Structural Network Disruptions in Survivors of Acute Lymphoblastic Leukemia with Chemotherapy Treatment

OBJECTIVES

Neuroimaging studies of acute lymphoblastic leukemia (ALL) during chemotherapy treatment have shown alterations in structure, function, and connectivity in several brain regions, suggesting neurobiological impairment that might influence the large-scale brain network. This study aimed to detect the alterations in the topological organization of structural covariance networks of ALL patients.

METHODS

This study included 28 ALL patients undergoing chemotherapy and 20 matched healthy controls. We calculated the gray matter volume of 90 brain regions based on an automated anatomical labeling template and applied graph theoretical analysis to compare the topological parameters of the gray matter structural networks between the two groups.

RESULTS

The results demonstrated that both the ALL and healthy control groups exhibited a small-world topology across the range of densities. Compared to healthy controls, ALL patients had less highly interactive nodes and a reduced degree/betweenness in temporal regions, which may contribute to impaired memory and executive functions in these patients.

CONCLUSION

These results reveal that ALL patients undergoing chemotherapy treatment may have decreased regional connectivity and reduced efficiency of their structural covariance network. This is the first report of anomalous large-scale gray matter structural networks in ALL patients undergoing chemotherapy treatment and provides new insights regarding the neurobiological mechanisms underlying the chemo-brain network.

Neuroanatomical abnormalities related to dexamethasone exposure in survivors of childhood acute lymphoblastic leukemia

Survivors of childhood acute lymphoblastic leukemia (ALL) treated with chemotherapy only are at risk for neurocognitive impairment. Regions of interest were identified a priori based on glucocorticoid receptor distribution, and sex-stratified multivariable linear regression models were used to test associations between brain MRI morphology and total number of intrathecal injections, and serum concentration of dexamethasone and methotrexate. Compared with controls, ALL survivors have persistently smaller volumes in the bilateral cerebellum (P < 0.005), hippocampal subregions (P < 0.03), temporal lobe regions (P < 0.03), frontal lobe regions (P < 0.04), and parietal lobe regions (precuneus; P < 0.002). Long-term problems with learning may be related to residual posttreatment brain differences.

Cerebral microbleeds in adult survivors of childhood acute lymphoblastic leukemia treated with cranial radiation

Cranial radiation therapy is associated with white matter-specific brain injury, cortical volume loss, mineralization, microangiopathy and neurocognitive impairment in survivors of childhood acute lymphoblastic leukemia. In this retrospective cross-sectional analysis, neurocognitive testing and 3 T brain MRI’s were obtained in 101 survivors treated with cranial radiation. Small focal intracerebral hemorrhages only visible on exquisitely sensitive MRI sequences were identified and localized using susceptibility weighted imaging. Modified Poisson regression was used to assess the effect of cranial radiation on cumulative number and location of microbleeds in each brain region, and multiple linear regression was used to evaluate microbleeds on neurocognitive outcomes, adjusting for age at diagnosis and sex. At least one microbleed was present in 85% of survivors, occurring more frequently in frontal lobes. Radiation dose of 24 Gy conveyed a 5-fold greater risk (95% CI 2.57–10.32) of having multiple microbleeds compared to a dose of 18 Gy. No significant difference was found in neurocognitive scores with either the absence or presence of microbleeds or their location. Greater prevalence of microbleeds in our study compared to prior reports is likely related to longer time since treatment, better sensitivity of SWI for detection of microbleeds and the use of a 3 T MRI platform.

Changes in neurocognitive function and central nervous system structure in childhood acute lymphoblastic leukaemia survivors after treatment: a meta-analysis

Acute lymphoblastic leukaemia (ALL) is the most common malignancy in children. Although the survival rate has increased dramatically over the last decades, patients struggle with the adverse side effects of treatment. Treatment for ALL includes chemotherapy and irradiation - both of which are linked to cognitive impairments and alterations in central nervous system (CNS) structure and function detected by neuroimaging and in neurocognitive studies. The present article is a meta-analysis of the existing evidence for the mechanisms underlying changes in the CNS and neurocognitive function in ALL survivors after treatment. We found that compared with controls, ALL survivors develop: (i) cognitive sequelae in intelligence, academics, attention, memory, processing speed and executive function domains; (ii) decreased grey and white matter volume in cortical and several subcortical brain regions, with functional changes particularly in frontal regions and the hippocampus; (iii) neurocognitive impairments related to CNS changes; and (iv) reduction, but not resolution, of late neurocognitive sequelae in patients in whom prophylactic irradiation was replaced by systemic/intrathecal chemotherapy. Continued work with advanced functional magnetic resonance imaging techniques will hopefully allow the detection of early CNS changes as biomarkers to help guide early diagnosis and intervention for neurocognitive defects in patients with childhood ALL.

A Review of Chronic Leukoencephalopathy among Survivors of Childhood Cancer

Currently, there are an estimated 400,000 long-term survivors of childhood cancer in the United States. Chronic leukoencephalopathy is a potential devastating late effect that can manifest as a range of neurological and neurocognitive sequelae. Survivors of the acute lymphocytic leukemia, central nervous system tumors, and stem cell transplant have frequently been exposed to cranial radiation, systemic and intrathecal chemotherapy, which places them at risk of developing chronic leukoencephalopathy. Defining leukoencephalopathy and its neuroimaging characteristics, the population of survivors at risk, its long-term consequences, and identifying prevention and intervention strategies can potentially mitigate the morbidity of these survivors. Better understanding of those at risk of leukoencephalopathy and its symptoms can lead to an improved quality of life for these cancer survivors.

Melatonin rescued methotrexate-induced spatial deficit and hyperhomocysteinemia and increased asymmetric dimethylarginine in plasma and dorsal hippocampus in developing rats

AIMS

With the improvement of the survival rates in children acute lymphoblastic leukemia (ALL), some children ALL survivors show impaired cognitive function. Methotrexate (MTX), an essential component in ALL treatment, has been reported to be related to neurologic sequelae and to increased oxidative stress through its interactions with enzymes in the folate pathway. Asymmetric dimethylarginine (ADMA) is the main endogenous inhibitor of nitric oxide synthase, and increased ADMA may result from increased oxidants. Melatonin is an antioxidant; however, its role in MTX neuropathy is not well studied. We developed a rat model mimicking child ALL treatment to explore peripheral and central homocysteine and ADMA regulation after MTX and found potential treatment choice.

MAIN METHODS

Preweaning male Sprague-Dawley rats were used in this study. Experiment 1 evaluated spatial performance in rats with intrathecal (IT) MTX, intraperitoneal (IP) MTX, or combined IT and IP MTX, protocols mimicking ALL treatment in children. Experiment 2 focused on rats with combined IT and IP MTX, evaluating spatial performance and plasma and dorsal hippocampal homocysteine and ADMA levels, their regulation, and the protective effect of melatonin.

KEY FINDINGS

Combined IT and IP MTX treatment caused in spatial deficits in developing rats, and melatonin restored the spatial performance. Alterations in peripheral and central homocysteine and ADMA concentrations and their regulation were found and could be alleviated by melatonin treatment.

SIGNIFICANCES

Combined IP and IT MTX treatment caused spatial deficits in developing rats. Melatonin could restore spatial performance through alleviating the effects on the imbalance of oxidative stress.

Early Imaging Based Predictive Modeling of Cognitive Performance Following Therapy for Childhood ALL

In the United States, Acute Lymphoblastic Leukemia (ALL), the most common child and adolescent malignancy, accounts for roughly 25% of childhood cancers diagnosed annually with a 5-year survival rate as high as 94% [1]. This improved survival rate comes with an increased risk for delayed neurocognitive effects in attention, working memory, and processing speed [2]. Predictive modeling and characterization of neurocognitive effects are critical to inform the family and also to identify patients for interventions targeting. Current state-of-the-art methods mainly use hypothesis-driven statistical testing methods to characterize and model such cognitive events. While these techniques have proven to be useful in understanding cognitive abilities, they are inadequate in explaining causal relationships, as well as individuality and variations. In this study, we developed multivariate data-driven models to measure the late neurocognitive effects of ALL patients using behavioral phenotypes, Diffusion Tensor Magnetic Resonance Imaging (DTI) based tractography data, morphometry statistics, tractography measures, behavioral, and demographic variables. Alongside conventional machine learning and graph mining, we adopted "Stability Selection" to select the most relevant features and choose models that are consistent over a range of parameters. The proposed approach demonstrated substantially improved accuracy (13% - 26%) over existing models and also yielded relevant features that were verified by domain experts.

Brain Connectivity and Cognitive Flexibility in Nonirradiated Adult Survivors of Childhood Leukemia

Background

This study aimed to assess functional and structural brain connectivity in adult childhood leukemia survivors and the link with cognitive functioning and previously identified risk factors such as intrathecal methotrexate dose and age at start of therapy.

Methods

Thirty-one nonirradiated adult childhood leukemia survivors and 35 controls underwent cognitive testing and multimodal magnetic resonance imaging (resting state functional MRI, T1-weighted, diffusion-weighted, and myelin water imaging [MWI]). Analyses included dual regression, voxel-based morphometry, advanced diffusion, and MWI modeling techniques besides stepwise discriminant function analysis to identify the most affected executive cognitive domain. Correlations with discrete intrathecal MTX doses and (semi)continuous variables were calculated using Spearman's rank and Pearson's correlation, respectively. All correlation tests were two-sided. Positive and negative T-contrasts in functional and structural MRI analysis were one-sided.

Results

Survivors demonstrated lower functional connectivity between the default mode network (DMN) and inferior temporal gyrus (ITG; P < .008). Additionally, we observed higher fractional anisotropy (FA; P = .04) and lower orientation dispersion index (ODI; P = .008) at the left centrum semiovale, which could-given that several fiber bundles cross this region-suggest selective reduced integrity of the respective white matter tracts. Set shifting reaction time, a measure of cognitive flexibility, was mostly impaired and correlated with lower FA (r = -0.53, P = .003) and higher ODI (r = 0.40, P = .04) in survivors but not with DMN-ITG connectivity. There were no statistically significant differences between survivors and controls in WM or GM volume, nor was there a statistically significant correlation between imaging measurements and age at start of therapy or intrathecal methotrexate dose.

Conclusions

Adult, nonirradiated childhood leukemia survivors show altered brain connectivity, which is linked with cognitive flexibility.

Brain morphology and information processing at the completion of chemotherapy-only treatment for pediatric acute lymphoblastic leukemia

Background: Approximately 50% of survivors of childhood acute lymphoblastic leukemia (ALL) demonstrate cognitive impairments. However, the trajectory of change and contributing neuropathology is unclear, limiting our ability to tailor intervention content and timing. This study aimed to explore information processing abilities and brain morphology early post-treatment for pediatric ALL. Procedure: Twenty-one children at the end of ALL treatment and 18 controls underwent neuropsychological assessment. A subset also completed structural magnetic resonance imaging. Results: A principal component analysis generated two cognitive factors: information processing capacity and information processing speed. Compared to control group, the ALL group displayed deficits in capacity, but not speed. No group differences were identified in morphology. No relationship was identified between capacity or speed and morphology. Conclusion: Early cognitive intervention should target information processing abilities using a system-wide approach. Future studies should employ alternative imaging techniques sensitive to white-matter microstructure when exploring pathology underlying information processing deficits.

Influence of genetic factors on long-term treatment related neurocognitive complications, and on anxiety and depression in survivors of childhood acute lymphoblastic leukemia: The Petale study

BACKGROUND

A substantial number of survivors of childhood acute lymphoblastic leukemia suffer from treatment-related late adverse effects including neurocognitive impairment. While multiple studies have described neurocognitive outcomes in childhood acute lymphoblastic leukemia (ALL) survivors, relatively few have investigated their association with individual genetic constitution.

METHODS

To further address this issue, genetic variants located in 99 genes relevant to the effects of anticancer drugs and in 360 genes implicated in nervous system function and predicted to affect protein function, were pooled from whole exome sequencing data of childhood ALL survivors (PETALE cohort) and analyzed for an association with neurocognitive complications, as well as with anxiety and depression. Variants that sustained correction for multiple testing were genotyped in entire cohort (n = 236) and analyzed with same outcomes.

RESULTS

Common variants in MTR, PPARA, ABCC3, CALML5, CACNB2 and PCDHB10 genes were associated with deficits in neurocognitive tests performance, whereas a variant in SLCO1B1 and EPHA5 genes was associated with anxiety and depression. Majority of associations were modulated by intensity of treatment. Associated variants were further analyzed in an independent SJLIFE cohort of 545 ALL survivors. Two variants, rs1805087 in methionine synthase, MTR and rs58225473 in voltage-dependent calcium channel protein encoding gene, CACNB2 are of particular interest, since associations of borderline significance were found in replication cohort and remain significant in combined discovery and replication groups (OR = 1.5, 95% CI, 1-2.3; p = 0.04 and; OR = 3.7, 95% CI, 1.25-11; p = 0.01, respectively). Variant rs4149056 in SLCO1B1 gene also deserves further attention since previously shown to affect methotrexate clearance and short-term toxicity in ALL patients.

CONCLUSIONS

Current findings can help understanding of the influence of genetic component on long-term neurocognitive impairment. Further studies are needed to confirm whether identified variants may be useful in identifying survivors at increased risk of these complications.

Educational attainment of childhood cancer survivors: A systematic review

Background

Advances in treatment mean that most children diagnosed with cancer during childhood survive. Therefore, it is increasingly important to examine the long‐term consequences of childhood cancer, including educational attainment. This systematic review investigated whether the educational attainment of childhood cancer survivors differ from the cancer‐free population.

Design/methods

We searched seven databases for articles published from January 2005 to August 2018. We identified full papers in English, reporting primary data on academic attainment of adult survivors of childhood cancer, compared to a control group. Quality appraisal was conducted using the Newcastle‐Ottawa Scale.

Results

Fourteen studies met the inclusion criteria. Nine papers included patients with various types of cancers, four focused on a single type of cancer, and one on patients who underwent stem cell transplantation.

Of the 14 papers, 2 studies were considered good quality, 10 were considered adequate quality, and 2 were considered poor quality. Four studies reported more favorable educational attainment among survivors while six did not report significant differences. Less favorable attainment was consistently reported for CNS survivors in four studies.

Conclusion

The literature does not provide a clear pattern of the long‐term consequences of childhood cancer on education attainment. While this may suggest that there is no consistent difference between the education attainment of cancer survivors and controls, it may also be the result of limitations in the existing research. To better assess the education attainment of survivors, there is a need for high‐quality studies, with appropriate comparators, and standardized measures of education attainment across countries.

Developmental origins and emerging therapeutic opportunities for childhood cancer

Cancer is the leading disease-related cause of death in children in developed countries. Arising in the context of actively growing tissues, childhood cancers are fundamentally diseases of dysregulated development. Childhood cancers exhibit a lower overall mutational burden than adult cancers, and recent sequencing studies have revealed that the genomic events central to childhood oncogenesis include mutations resulting in broad epigenetic changes or translocations that result in fusion oncoproteins. Here, we will review the developmental origins of childhood cancers, epigenetic dysregulation in tissue stem/precursor cells in numerous examples of childhood cancer oncogenesis and emerging therapeutic opportunities aimed at both cell-intrinsic and microenvironmental targets together with new insights into the mechanisms underlying long-term sequelae of childhood cancer therapy.

Changes in cortical thickness and volume after cranial radiation treatment: A systematic review

Cognitive decline has a clear impact on quality of life in patients who have received cranial radiation treatment. The pathophysiological process is most likely multifactorial, with a possible role for decreased cortical thickness and volume. As radiotherapy treatment systems are becoming more sophisticated, precise sparing of vulnerable regions and tissue is possible. This allows radiation oncologists to make treatment more patient-tailored. A systematic search was performed to collect and review all available evidence regarding the effect of cranial radiation treatment on cortical thickness and volume. We searched the Pubmed, Embase and Cochrane databases, with an additional reference check in the Scopus database. Studies that examined cortical changes on MRI within patients as well as between treated and non-treated patients were included. The quality of the studies was assessed with a checklist specially designed for this review. No meta-analysis was performed due to the lack of randomised trials. Out of 1915 publications twenty-one papers were selected, of which fifteen observed cortical changes after radiation therapy. Two papers reported radiation-dependent decrease in cortical thickness within patients one year after radiation treatment, suggesting a clear relation between the two. However, study quality was considered mostly suboptimal, and there was great inhomogeneity between the included studies. This means that, although there has been increasing interest in the effects of radiation treatment on cortex morphology, no reliable conclusion can be drawn based on the currently available evidence. This calls for more research, preferably with a sufficiently large patient population, and adequate methodology.

Exercise ameliorates neurocognitive impairments in a translational model of pediatric radiotherapy

Background

While cranial radiation therapy (CRT) is an effective treatment, healthy areas surrounding irradiation sites are negatively affected. Frontal lobe functions involving attention, processing speed, and inhibition control are impaired. These deficits appear months to years after CRT and impair quality of life. Exercise has been shown to rejuvenate the brain and aid in recovery post-injury through its effects on neurogenesis and cognition.

Methods

We developed a juvenile rodent CRT model that reproduces neurocognitive deficits. Next, we utilized the model to test whether exercise ameliorates these deficits. Fischer rats (31 days old) were irradiated with a fractionated dose of 4 Gy × 5 days, trained and tested at 6, 9, and 12 months post-CRT using 5-choice serial reaction time task. After testing, fixed rat brains were imaged using diffusion tensor imaging and immunohistochemistry.

Results

CRT caused early and lasting impairments in task acquisition, accuracy, and latency to correct response, as well as causing stunting of growth and changes in brain volume and diffusion. Exercising after irradiation improved acquisition, behavioral control, and processing speed, mitigated the stunting of brain size, and increased brain fiber numbers compared with sedentary CRT values. Further, exercise partially restored global connectome organization, including assortativity and characteristic path length, and while it did not improve the specific regional connections that were lowered by CRT, it appeared to remodel these connections by increasing connectivity between alternate regional pairs.

Conclusions

Our data strongly suggest that exercise may be useful in combination with interventions aimed at improving cognitive outcome following pediatric CRT.

Chemotherapy and the pediatric brain

Survival rates of children with cancer are steadily increasing. This urges our attention to neurocognitive and psychiatric outcomes, as these can markedly influence the quality of life of these children. Neurobehavioral morbidity in childhood cancer survivors affects diverse aspects of cognitive function, which can include attention, memory, processing speed, intellect, academic achievement, and emotional health. Reasons for neurobehavioral morbidity are multiple with one major contributor being chemotherapy-induced central nervous system (CNS) toxicity. Clinical studies investigating the effects of chemotherapy on the CNS in children with cancer have reported causative associations with the development of leukoencephalopathies as well as smaller regional grey and white matter volumes, which have been found to correlate with neurocognitive deficits.Preclinical work has provided compelling evidence that chemotherapy drugs are potent neuro- and gliotoxins in vitro and in vivo and can cause brain injury via excitotoxic and apoptotic mechanisms. Furthermore, chemotherapy triggers DNA (deoxyribonucleic acid) damage directly or through increased oxidative stress. It can shorten telomeres and accelerate cell aging, cause cytokine deregulation, inhibit hippocampal neurogenesis, and reduce brain vascularization and blood flow. These mechanisms, when allowed to operate on the developing brain of a child, have high potential to not only cause brain injury, but also alter crucial developmental events, such as myelination, synaptogenesis, neurogenesis, cortical thinning, and formation of neuronal networks.This short review summarizes key publications describing neurotoxicity of chemotherapy in pediatric cancers and potential underlying pathomechanisms.

The Impact of Persistent Leukoencephalopathy on Brain White Matter Microstructure in Long-Term Survivors of Acute Lymphoblastic Leukemia Treated with Chemotherapy Only

BACKGROUND AND PURPOSE

Survivors of acute lymphoblastic leukemia are at risk for neurocognitive deficits and leukoencephalopathy. We performed a longitudinal assessment of leukoencephalopathy and its associations with long-term brain microstructural white matter integrity and neurocognitive outcomes in survivors of childhood acute lymphoblastic leukemia treated on a modern chemotherapy-only protocol.

MATERIALS AND METHODS

One hundred seventy-three survivors of acute lymphoblastic leukemia (49% female), treated on a chemotherapy-only protocol, underwent brain MR imaging during active therapy and repeat imaging and neurocognitive testing at follow-up (median, 13.5 years of age; interquartile range, 10.7-17.6 years; median time since diagnosis, 7.5 years; interquartile range, 6.3-9.1 years). Persistence of leukoencephalopathy was examined in relation to demographic and treatment data and to brain DTI in major fiber tracts and neurocognitive testing at follow-up.

RESULTS

Leukoencephalopathy was found in 52 of 173 long-term survivors (30.0%) and persisted in 41 of 52 (78.8%) who developed it during therapy. DTI parameters were associated with leukoencephalopathy in multiple brain regions, including the corona radiata (fractional anisotropy, P = .001; mean diffusivity, P < .001), superior longitudinal fasciculi (fractional anisotropy, P = .02; mean diffusivity, P < .001), and superior fronto-occipital fasciculi (fractional anisotropy, P = .006; mean diffusivity, P < .001). Mean diffusivity was associated with neurocognitive impairment including in the genu of the corpus callosum (P = .04), corona radiata (P = .02), and superior fronto-occipital fasciculi (P = .02).

CONCLUSIONS

Leukoencephalopathy during active therapy and neurocognitive impairment at long-term follow-up are associated with microstructural white matter integrity. DTI may be more sensitive than standard MR imaging for detection of clinically consequential white matter abnormalities in childhood acute lymphoblastic leukemia survivors treated with chemotherapy and in children undergoing treatment.

DIVERGT screening procedure predicts general cognitive functioning in adult long-term survivors of pediatric acute lymphoblastic leukemia: A PETALE study

BACKGROUND

Acute lymphoblastic leukemia (ALL) is the most common cancer in children. Because of major improvements in treatment protocols, the survival rate now exceeds 80%. However, ALL treatments can cause long-term neurocognitive sequelae, which negatively impact academic achievement and quality of life. Therefore, cognitive sequelae need to be carefully evaluated. The DIVERGT is a battery of tests proposed as a screening tool, sensitive to executive function impairments in children and adolescent cancer survivors. Our study aimed at verifying the predictive value of the DIVERGT on general cognitive functioning in adult long-term survivors of ALL.

METHODS

ALL survivors completed the DIVERGT 13.4 years, on average, after remission (N = 247). In addition, 49 of these survivors (equally selected amongst those with low, average, and high DIVERGT scores) as well as 29 controls completed a more comprehensive neuropsychological evaluation within a 3-year period from DIVERGT administration. Multivariate regression analysis was used to assess the predictive value of the DIVERGT on general intelligence, mathematics, verbal memory, and working memory. As a follow-up analysis, three performance groups were created based on the DIVERGT results. Multivariate analysis of variance (MANOVA) assessed neuropsychological differences between groups.

RESULTS

The DIVERGT accurately predicted General Ability Index (GAI) (P < 0.0001), mathematics (P < 0.0001) and verbal memory (P = 0.045). Moreover, the low-performance group consistently had poorer performance than the high-performance and control groups on the neuropsychological tests.

CONCLUSION

The DIVERGT is a useful, time-effective screening battery for broader neurocognitive impairments identification in long-term adult ALL survivors. It could be implemented as routine examination in cancer follow-up clinics.

Brain Network Connectivity and Executive Function in Long-Term Survivors of Childhood Acute Lymphoblastic Leukemia

Chemotherapeutic agents used to treat acute lymphoblastic leukemia (ALL), the most common cancer affecting young children, have been associated with long-term cognitive impairments that reduce quality of life. Executive dysfunction is one of the most consistently observed deficits and can have substantial and pervasive effects on academic success, occupational achievement, psychosocial function, and psychiatric status. We examined the neural mechanisms of executive dysfunction by measuring structural and functional connectomes in 161 long-term survivors of pediatric ALL, age 8-21 years, who were treated on a single contemporary chemotherapy-only protocol for standard/high- or low-risk disease. Lower global efficiency, a measure of information exchange and network integration, of both structural and functional connectomes was found in survivors with executive dysfunction compared with those without dysfunction (p < 0.046). Patients with standard/high- versus low-risk disease and those who received greater number of intrathecal treatments containing methotrexate had the lowest network efficiencies. Patients with executive dysfunction also showed hyperconnectivity in sensorimotor, visual, and auditory-processing regions (p = 0.037) and poor separation between sensorimotor, executive/attention, salience, and default mode networks (p < 0.0001). Connectome disruption was consistent with a pattern of delayed neurodevelopment that may be associated with reduced resilience, adaptability, and flexibility of the brain network. These findings highlight the need for interventions that will prevent or manage cognitive impairment in survivors of pediatric acute lymphoblastic leukemia.