Region-specific radiotherapy and neuropsychological outcomes in adult survivors of childhood CNS malignancies

Neuropsychological Consequences for Survivors of Childhood Brain Tumor in Malaysia

Objective: This study aimed to evaluate neuropsychological consequences in survivors of childhood brain tumor.

Method: A case-control study was conducted over a period of 4 months in a tertiary referral center in Kuala Lumpur, Malaysia. Fourteen survivors of childhood brain tumor aged 7–18 years, who were off-treatment for at least 1 year and were in remission, and 31 unrelated healthy controls were recruited. The median age at diagnosis was 8.20 years (range: 0.92–12.96 years). The diagnoses of brain tumors were medulloblastoma, germ cell tumor, pineocytoma, pilocystic astrocytoma, suprasellar germinoma, and ependymoma. Eleven survivors received central nervous system irradiation. Seven tasks were selected from the Amsterdam Neuropsychological Tasks program to evaluate alertness (processing speed), and major aspects of executive functioning, such as working memory capacity, inhibition, cognitive flexibility, and sustained attention. Speed, stability and accuracy of responses were the main outcome measures.

Results: Survivors of childhood brain tumor showed statistically significant poorer performance on all tasks compared to healthy controls. Both processing speed and accuracy were impaired in the survivors, in particular under more complex task conditions. The survivors demonstrated deficits in alertness, sustained attention, working memory capacity, executive visuomotor control, and cognitive flexibility. Longer duration off treatment appeared to be correlated with poorer alertness, memory capacity, and inhibition.

Conclusion: Survivors of childhood brain tumor in our center showed impaired neuropsychological functioning. Development of less toxic treatment protocols is important to prevent late effects of cognitive deficits in survivors of childhood brain tumor.

Neuropsychological consequences of childhood medulloblastoma and possible interventions: A review

BACKGROUND

Children who have been treated for a medulloblastoma often suffer long-term cognitive impairments that often negatively affect their academic performance and quality of life. In this article, we will review the neuropsychological consequences of childhood medulloblastoma and discuss the risk factors known to influence the presence and severity of these cognitive impairments and possible interventions to improve their quality of life.

METHODS

This narrative review was based on electronic searches of PubMed to identify all relevant studies.

RESULTS

Although many types of cognitive impairments often emerge during a child's subsequent development, the core cognitive domains that are most often affected in children treated for a medulloblastoma are processing speed, attention and working memory. The emergence and magnitude of these deficits varies greatly among patients. They are influenced by demographic (age at diagnosis, parental education), medical and treatment-related factors (perioperative complications, including posterior fossa syndrome, radiation therapy dose, etc.), and the quality of interventions such as school adaptations provided to the child or rehabilitation programs that focus on cognitive skills, behavior and psychosocial functioning.

CONCLUSION

These patients require specialized and coordinated multidisciplinary rehabilitation follow-up that provides timely and adapted assessments and culminates in personalized intervention goals being set with the patient and the family. Follow-up should be continued until referral to adult services.

Hippocampal sparing in stereotactic radiotherapy for brain metastases: To contour or not contour the hippocampus?

PURPOSE

The aim of our study was to evaluate hippocampal irradiation in patients treated with fractionated stereotactic brain radiotherapy.

PATIENTS AND METHODS

Retrospective hippocampal dosimetric analysis performed on 22 patients with one to four brain metastases treated with fractionated stereotactic radiotherapy using volumetric intensity-modulated arc therapy. Original plans did not include hippocampus as avoidance structure in optimization criteria; hippocampus was retrospectively delineated on magnetic resonance coregistered with planning CT and using as reference the RTOG 0933 atlas. Hippocampus was defined both as a single and as pair organ. Constraints analysed were: Dmax<16Gy, D40%<7.3Gy, D100%=Dmin<9Gy. Assuming a α/β ratio of 2Gy, biologically equivalent dose in 2Gy fractions was calculated. Hippocampal-sparing plans were developed in cases where hippocampal constraints were not respected in the original plan.

RESULTS

Among constraints analysed Dmax and D40% have been exceeded in ten out of 22 cases. The constraints were not respected in patients with more than one metastatic lesion and in three patients with only one lesion. Considering all exceeded constraints values in non-hippocampal sparing plans, the 50% of them was respected after replanning. No significant differences were found among conformity and homogeneity index between non-hippocampal sparing and hippocampal sparing plans.

CONCLUSION

Volumetric intensity-modulated arc therapy hippocampal sparing plans significantly decreases dose to hippocampus assuring an equal target coverage and organs at risk avoiding.

The EPTN consensus-based atlas for CT- and MR-based contouring in neuro-oncology

PURPOSE

To create a digital, online atlas for organs at risk (OAR) delineation in neuro-oncology based on high-quality computed tomography (CT) and magnetic resonance (MR) imaging.

METHODS

CT and 3 Tesla (3T) MR images (slice thickness 1 mm with intravenous contrast agent) were obtained from the same patient and subsequently fused. In addition, a 7T MR without intravenous contrast agent was obtained from a healthy volunteer. Based on discussion between experienced radiation oncologists, the clinically relevant organs at risk (OARs) to be included in the atlas for neuro-oncology were determined, excluding typical head and neck OARs previously published. The draft atlas was delineated by a senior radiation oncologist, 2 residents in radiation oncology, and a senior neuro-radiologist incorporating relevant available literature. The proposed atlas was then critically reviewed and discussed by European radiation oncologists until consensus was reached.

RESULTS

The online atlas includes one CT-scan at two different window settings and one MR scan (3T) showing the OARs in axial, coronal and sagittal view. This manuscript presents the three-dimensional descriptions of the fifteen consensus OARs for neuro-oncology. Among these is a new OAR relevant for neuro-cognition, the posterior cerebellum (illustrated on 7T MR images).

CONCLUSION

In order to decrease inter- and intra-observer variability in delineating OARs relevant for neuro-oncology and thus derive consistent dosimetric data, we propose this atlas to be used in photon and particle therapy. The atlas is available online at www.cancerdata.org and will be updated whenever required.

A role for endothelial cells in radiation-induced inflammation

PURPOSE

To unravel the role of the vasculature in radiation-induced brain tissue damage.

MATERIALS AND METHODS

Postnatal day 14 mice received a single dose of 10 Gy cranial irradiation and were sacrificed 6 h, 24 h or 7 days post-irradiation. Endothelial cells were isolated from the hippocampus and cerebellum using fluorescence-activated cell sorting, followed by cell cycle analysis and gene expression profiling.

RESULTS

Flow cytometric analysis revealed that irradiation increased the percentage of endothelial cells, relative to the whole cell population in both the hippocampus and the cerebellum. This change in cell distribution indicates that other cell types are more susceptible to irradiation-induced cell death, compared to endothelial cells. This was supported by data showing that genes involved in endothelial cell-specific apoptosis (e.g. Smpd1) were not induced at any time point investigated but that genes involved in cell-cycle arrest (e.g. Cdkn1a) were upregulated at all investigated time points, indicating endothelial cell repair. Inflammation-related genes, on the other hand, were strongly induced, such as Ccl2, Ccl11 and Il6.

CONCLUSIONS

We conclude that endothelial cells are relatively resistant to ionizing radiation but that they play an active, hitherto unknown, role in the inflammatory response after irradiation. In the current study, this was shown in both the hippocampus, where neurogenesis and extensive cell death after irradiation occurs, and in the cerebellum, where neurogenesis no longer occurs at this developmental age.

Relationships between Regional Radiation Doses and Cognitive Decline in Children Treated with Cranio-Spinal Irradiation for Posterior Fossa Tumors

Pediatric posterior fossa tumor (PFT) survivors who have been treated with cranial radiation therapy often suffer from cognitive impairments that might relate to IQ decline. Radiotherapy (RT) distinctly affects brain regions involved in different cognitive functions. However, the relative contribution of regional irradiation to the different cognitive impairments still remains unclear. We investigated the relationships between the changes in different cognitive scores and radiation dose distribution in 30 children treated for a PFT. Our exploratory analysis was based on a principal component analysis (PCA) and an ordinary least square regression approach. The use of a PCA was an innovative way to cluster correlated irradiated regions due to similar radiation therapy protocols across patients. Our results suggest an association between working memory decline and a high dose (equivalent uniform dose, EUD) delivered to the orbitofrontal regions, whereas the decline of processing speed seemed more related to EUD in the temporal lobes and posterior fossa. To identify regional effects of RT on cognitive functions may help to propose a rehabilitation program adapted to the risk of cognitive impairment.

A prospective study of corpus callosum regional volumes and neurocognitive outcomes following cranial radiation for pediatric brain tumors

PURPOSE/OBJECTIVE(S)

Cranial radiation therapy (CRT) may disrupt the corpus callosum (CC), which plays an important role in basic motor and cognitive functions. The aim of this prospective longitudinal study was to assess changes in CC mid-sagittal areas, CC volumes, and performance on neuropsychological (NP) tests related to the CC in children following CRT.

MATERIALS/METHODS

Twelve pediatric patients were treated with CRT for primary brain malignancies. Thirteen age-matched healthy volunteers served as controls. Brain MRIs and NP assessment emphasizing motor dexterity, processing speed, visuomotor integration, and working memory (visual and verbal) were performed at baseline and at 6, 15, and 27 months following completion of CRT. Linear mixed effects (LME) analyses were used to evaluate patient NP performance and changes in regional CC volumes (genu, anterior body, mid-body, posterior body, and splenium) and mid-sagittal areas over time and with radiation doses, correcting for age at CRT start.

RESULTS

The mean age at CRT was 9.41 (range 1.2-15.7) years. The median prescription dose was 54 (range 18-59.4) Gy. LME analysis revealed a significant decrease in overall CC volumes over time (p < 0.00001), with no overall effect of radiation dose. Analysis of individual CC regions demonstrated a significant decrease in all regional volumes over time (p < 0.00001) in patients, with no effect of radiation dose. Only in the splenium was there a trend toward a dose-dependent effect (p = 0.093). Patients had significantly reduced NP performance across visits-most notably in motor dexterity and visual working memory (both p < 0.0001).

CONCLUSIONS

These prospective data demonstrate a significant decrease in CC regional volumes after CRT, with associated decline in neurocognitive function, most notably in manual dexterity, attention, and working memory. Further prospective study of larger cohorts of patients is needed to establish the relationship between CRT dose, neuroanatomical, and functional changes in the CC.

Chemoradiation impairs normal developmental cortical thinning in medulloblastoma

Medulloblastoma patients are treated with surgery, radiation and chemotherapy. Radiation dose to the temporal lobe may be associated with neurocognitive sequelae. Longitudinal changes of temporal lobe cortical thickness may result from neurodevelopmental processes such as synaptic pruning. This study applies longitudinal image analysis to compare developmental change in cortical thickness in medulloblastoma (MB) patients who were treated by combined modality therapy to that of cerebellar juvenile pilocytic astrocytoma (JPA) patients who were treated by surgery alone. We hypothesized that the rates of developmental change in cortical thickness would differ between these two groups. This retrospective cohort study assessed changes in cortical thickness over time between MB and JPA patients. High-resolution magnetic resonance (MR) images of 14 MB and 7 JPA subjects were processed to measure cortical thickness of bilateral temporal lobe substructures. A linear mixed effects model was used to identify differences in substructure longitudinal changes in cortical thickness. The left temporal lobe exhibited overall increased cortical thickness in MB patients relative to JPA patients who showed overall cortical thinning (mean annual cortical thickness change: MB 0.14 mm/year versus JPA -0.018 mm/year across all substructures), particularly in the inferior temporal lobe substructures (p < 0.0001). The cortical thickness change of the right temporal lobe substructures exhibited similar, though attenuated trends (p = 0.002). MB patients exhibit overall increased cortical thickness rather than cortical thinning as seen in JPA patients and as expected in normal cortical development. These observations are possibly due to chemoradiation induced-disruption of normal neuronal mechanisms. Longitudinal image analysis may identify early biomarkers for neurocognitive function with routine imaging.

Development of depression in survivors of childhood and adolescent cancer: a multi-level life course conceptual framework

As therapeutic and supportive care interventions become increasingly effective, growing numbers of childhood and adolescent cancer survivors face a myriad of physical and psychological sequelae secondary to their disease and treatment. Mental health issues, in particular, present a significant problem in this unique patient population, with depression affecting a sizable number of childhood and adolescent cancer survivors. Multiple key determinants impact a survivor's risk of developing depression, with variables traversing across biologic, individual, family, community, and global levels, as well as spanning throughout the life course of human development from the preconception and prenatal periods to adulthood. A multi-level life course conceptual model offers a valuable framework to identify and organize the diverse variables that modulate the risk of developing depression in survivors of childhood and adolescent cancer. This review describes the first multi-level life course perspective applied to development of depression in childhood and adolescent cancer survivors. This conceptual framework may be used to guide the investigation of mental health interventions for SCACs to ensure that key determinants of depression occurrence are adequately addressed across various levels and throughout the life trajectory.

Behavioral, Social, and Emotional Symptom Comorbidities and Profiles in Adolescent Survivors of Childhood Cancer: A Report From the Childhood Cancer Survivor Study

PURPOSE

In the general population, psychological symptoms frequently co-occur; however, profiles of symptom comorbidities have not been examined among adolescent survivors of childhood cancer.

PATIENTS AND METHODS

Parents of 3,893 5-year survivors of childhood cancer who were treated between 1970 and 1999 and who were assessed in adolescence (age 12 to 17 years) completed the Behavior Problems Index. Age- and sex-standardized z scores were calculated for symptom domains by using the Childhood Cancer Survivor Study sibling cohort. Latent profile analysis identified profiles of comorbid symptoms, and multivariable multinomial logistic regression modeling examined associations between cancer treatment exposures and physical late effects and identified symptom profiles. Odds ratios (ORs) and 95% CIs for latent class membership were estimated and analyses were stratified by cranial radiation therapy (CRT; CRT or no CRT).

RESULTS

Four symptoms profiles were identified: no significant symptoms (CRT, 63%; no CRT, 70%); elevated anxiety and/or depression, social withdrawal, and attention problems (internalizing; CRT, 31%; no CRT, 16%); elevated headstrong behavior and attention problems (externalizing; CRT, no observed; no CRT, 9%); and elevated internalizing and externalizing symptoms (global symptoms; CRT, 6%; no CRT, 5%). Treatment with ≥ 30 Gy CRT conferred greater risk of internalizing (OR, 1.7; 95% CI, 1.0 to 2.8) and global symptoms (OR, 3.2; 95% CI, 1.2 to 8.4). Among the no CRT group, corticosteroid treatment was associated with externalizing symptoms (OR, 1.9; 95% CI, 1.2 to 2.8) and ≥ 4.3 g/m(2) intravenous methotrexate exposure was associated with global symptoms (OR, 1.5; 95% CI, 0.9 to 2.4). Treatment late effects, including obesity, cancer-related pain, and sensory impairments, were significantly associated with increased risk of comorbid symptoms.

CONCLUSION

Behavioral, emotional, and social symptoms frequently co-occur in adolescent survivors of childhood cancer and are associated with treatment exposures and physical late effects. Assessment and consideration of symptom profiles are essential for directing appropriate mental health treatment for adolescent survivors.

Anaplastic Ependymoma in a Child With Sickle Cell Anemia: A Case Report Highlighting Treatment Challenges for Young Children With Central Nervous System Tumors and Underlying Vasculopathy

A 3-year-old boy with sickle cell anemia (SCA) presented with progressive daily emesis and was found to have an anaplastic ependymoma. Radiation therapy and chemotherapy are usually employed after subtotal resections of anaplastic ependymomas, although the benefits from chemotherapy are unclear. To mitigate the risks of adjuvant treatment in this patient at risk for SCA-associated vasculopathy, renal impairment, and other end-organ damage, proton beam irradiation without chemotherapy was chosen. Scheduled packed red blood cell transfusions were instituted to maintain sickle hemoglobin levels less than 30%. This case highlights treatment complexities for malignant brain tumors in patients predisposed to treatment-related adverse effects.

A Retrospective Evaluation of the Benefit of Referring Pediatric Cancer Patients to an External Proton Therapy Center

BACKGROUND

Pediatric cancer patients requiring radiation therapy (RT) have been routinely assessed and referred to proton therapy (PT) at an external institution. The benefit of the delivered PT compared to the state-of-the-art intensity modulated x-ray RT (XT) at the home institution was evaluated.

PROCEDURE

Twenty-four consecutive children referred for PT during 2010-2013 for craniospinal (CSI, n = 10), localized intracranial (IC, n = 7), head/neck (HN, n = 4) or parameningeal (PM, n = 3) lesions were included. The median age was 8 years (2-16 years). XT plans were generated for each patient, blinded to the PT delivered. Dosimetry, estimated growth hormone deficiency (GHD), and neurocognitive dysfunction (NCD) risks were compared for PT and XT (Wilcoxon).

RESULTS

PT started (median) 5 weeks (± 1.3 weeks, 95% CI) after referral. For CSI patients, PT was clearly superior to XT plans with median dose reductions for the heart, lungs and thyroid of 17, 2.5 and 18 Gy, respectively (P = 0.005). The median estimated NCD and GHD risks were 1-3 (max 16) and 2 (max 61) percentage points, respectively, lower for PT compared to XT. The median of the mean doses to the brain, cochleae and pituitary gland was lower with PT than XT for the IC, H/N and PM patients (P < 0.039). For a single IC patient, the dose to hippocampi and optic chiasm was higher for PT compared to XT.

CONCLUSIONS

PT clearly benefitted the patients studied, except for IC disease where differences between PT and XT were modest, and comparative PT and XT treatment planning is warranted prior to referral.

A prospective study on neurocognitive effects after primary radiotherapy in high-grade glioma patients

BACKGROUND

Neurocognition is a very important aspect of a brain tumor patient's quality of life following radiotherapy. The aim of the present study was to assess neurocognitive functions of patients diagnosed with high-grade gliomas undergoing radiotherapy by using the NeuroCogFx(®) test and to examine relevant dose/volume parameters as well as patient characteristics potentially influencing the neurological baseline status and subsequent outcome.

METHODS

The cohort consisted of 44 astrocytoma World Health Organization grade III/IV patients. The NeuroCogFx(®) test was carried out on patients during (N = 44) and after (N = 21) irradiation. The test examines verbal/figural/short-term/working memory, psychomotorical speed, selective attention and verbal speed. The results were compared with regular patient and treatment data with an emphasis on the dose applied to the hippocampus.

RESULTS

Overall there were only slight changes in the median test results when comparing the baseline to the follow-up tests. In the 'verbal memory test' lower percentile ranks were achieved in left-sided tumors compared to right-sided tumors (p = 0.034). Dexamethasone intake during radiotherapy was significantly correlated with the difference between the two test batteries. Concerning figural memory, a correlation was detected between decreased figural recognition and the radiation dose to the left hippocampus (p = 0.045).

CONCLUSION

We conclude that tumor infiltration of the hippocampus has an impact on neurocognitive function. However, treatment with radiotherapy seems to have less influence on cognitive outcome than expected.

The Adult Life After Childhood Cancer in Scandinavia (ALiCCS) Study: Design and Characteristics

BACKGROUND

During the last five decades, survival of childhood cancer has increased from 25% to 80%. At the same time, however, it has become evident that survivors experience a broad range of therapy-related late adverse health effects. The aim of the Adult Life after Childhood Cancer in Scandinavia (ALiCCS) study is to investigate long-term health consequences of past and current therapies in order to improve follow-up care of survivors and to reduce treatment-related morbidity of future patients.

PROCEDURE

Childhood cancer survivors were identified through the five Nordic cancer registries and a comparison cohort was established through random selection of cancer-free individuals from the civil registration systems. A unique personal identification number was used to link between different health registries. Abstraction of treatment information for a subset of survivors allows investigation of the association between the various components of cancer therapy and late occurring comorbidity.

RESULTS

The childhood cancer survivor cohort comprises 33,160 1-year survivors and the comparison cohort comprises 212,892 cancer free individuals from the general population. In the childhood cancer survivor cohort, all types of childhood cancer are represented including leukemia (21%), lymphoma (14%), central nervous system tumors (24%), sarcomas (5%), retinoblastoma (3%), and neuroblastoma (4%). Among the survivors, 22% have been followed beyond the age of 40 years.

CONCLUSION

The ALiCCS study constitutes a new large resource for research on late effects of childhood cancers that include all types of childhood malignancies and has followed a large proportion of the survivors well into late adulthood.

New considerations in radiation treatment planning for brain tumors: neural progenitor cell-containing niches

The purpose of this critical review is to explore the controversy regarding the relationship between radiation dose to the neural progenitor cell (NPC) niches and patient outcomes, in terms of both toxicity and tumor control. NPCs in the subventricular zone (SVZ) and hippocampus are paradoxically associated with long-term neurocognitive sequelae of brain irradiation, as well as resistance to therapy and tumor recurrence. The reconciliation of these somewhat opposing functions is challenging. Current literature suggests that radiation and other treatments against the NPC in the hippocampus and the SVZ may influence patient outcome. As a result, both the SVZ and the hippocampus could have important implications on radiation treatment planning strategies, and future laboratory and clinical evaluations will be critical in designing studies to optimize treatment outcome, effectiveness, and safety.

Understanding the Treatment Strategies of Intracranial Germ Cell Tumors: Focusing on Radiotherapy

Intracranial germ cell tumors (ICGCT) occur in 2-11% of children with brain tumors between 0-19 years of age. For treatment of germinoma, relatively low radiation doses with or without chemotherapy show excellent 10 year survival rate of 80-100%. Past studies showed that neoadjuvant chemotherapy combined with focal radiotherapy resulted in unacceptably high rates of periventricular tumor recurrence. The use of generous radiation volume which covers the whole ventricular space with later boost treatment to primary site is considered as standard treatment of intracranial germinomas. For non-germinomatous germ cell tumors (NGGCT), 10-year overall survival rate is still much inferior than that of intracranial germinoma despite intensive chemotherapy and high-dose radiotherapy. Craniospinal radiotherapy combined with cisplatin-based chemotherapy provides the best treatment outcome for NGGCT; 60-70% of overall survival rate. There is a debate on the surgical role whether surgery can contribute to improved treatment outcome of NGGCT when added to combined chemoradiotherapy. Because higher dose of radiotherapy is required for treatment of NGGCT than for germinoma, it is tested whether whole ventricular irradiation can replace craniospinal irradiation in intermediate risk group of NGGCT to minimize radiation-related late toxicity in the recent studies. To minimize the treatment-related neural deficit and late sequelae while maintaining long-term survival rate of ICGCT patients, optimized administration of chemotherapy and radiotherapy should be selected. Use of technically upgraded radiotherapy modalities such as intensity-modulated radiotherapy or proton beam therapy is expected to bring an improved neurocognitive outcome with longitudinal assessment of the patients.

Comparison of dose distributions hippocampus in high grade gliomas irradiation with linac-based imrt and volumetric arc therapy: a dosimetric study

The aim of this study was to assess the feasibility of sparing contralateral hippocampus during partial brain radiotherapy in high grade gliomas. 20 previously treated patients were replanned to 60 Gy in 30 fractions with sparing intensity-modulated radiotherapy (IMRT) and volumetric modulated arctherapy (VMAT) using the following planning objectives: 100 % of PTV covered by 95% isodose without violating organs at risk (OAR) and hot spot dose constraints. For each, standard intensity-modulated radiotherapy (IMRT) plans were generated, as well as sparing IMRT and VMAT plans which spared contralateral (hemispheric cases) hippocampus. When the three plans were compared, there was equivalent PTV coverage, homogeneity, and conformality. Sparing IMRT significantly reduced maximum, mean, V20, V30 and V40 hippocampus doses compared with standart IMRT and VMAT (p < 0.05). VMAT significantly reduced maximum left lens and mean eye doses compared with standart IMRT and sparing IMRT (p < 0.05). Brainstem, chiasm, left and right optic nerves, right eyes and lens doses were similar. VMAT significantly reduced monitor units compared with standart IMRT and sparing IMRT (p < 0.05). It is possible to spare contralateral hippocampus during PBRT for high grade gliomas using IMRT. This approach may reduce late cognitive sequelae of cranial radiotherapy.

Social competence in pediatric brain tumor survivors: application of a model from social neuroscience and developmental psychology

Pediatric brain tumor (BT) survivors are at risk for psychosocial late effects across many domains of functioning, including neurocognitive and social. The literature on the social competence of pediatric BT survivors is still developing and future research is needed that integrates developmental and cognitive neuroscience research methodologies to identify predictors of survivor social adjustment and interventions to ameliorate problems. This review discusses the current literature on survivor social functioning through a model of social competence in childhood brain disorder and suggests future directions based on this model. Interventions pursuing change in survivor social adjustment should consider targeting social ecological factors.

The potential for epigenetic analysis of paediatric CNS tumours to improve diagnosis, treatment and prognosis

Tumours of central nervous system (CNS) origin are the second most prevalent group of cancers in children, yet account for the majority of childhood cancer-related deaths. Such tumours show diverse location, cell type of origin, disease course and long-term outcome, both across and within tumour types, making treatment problematic and contributing to the relatively modest progress in reducing mortality over recent decades. As technological advances begin to reveal the genetic landscape of all cancers, it is becoming increasingly clear that genetic disruption represents only one 'layer' of molecular disruption associated with disease aetiology. Obtaining a full understanding of tumour behaviour requires an understanding of the cellular and molecular pathways disrupted during tumourigenesis, particularly in relation to gene expression. The utility of such an approach has allowed stratification of cancers such as medulloblastoma into subgroups based on molecular features, with potential to refine risk prediction. Given that epigenetic disruption is a universal feature of all human cancers, it is logical to speculate that interrogating epigenetic marks may help to further define the molecular profile, and therefore the clinical trajectory, of tumours. An integrated approach to build a molecular 'signature' of individual tumours that incorporates traditional morphological and demographic information, genetic and transcriptome analysis, in addition to epigenomics (DNA methylation and non-coding RNA analysis), offers tremendous promise to (i) inform treatment approach, (ii) facilitate accurate early identification (preferably at diagnosis) of variable risk groups (both good and poor prognosis groups), and (iii) track disease progression in childhood CNS tumours.

The Childhood Cancer Survivor Study-Neurocognitive Questionnaire (CCSS-NCQ) revised: item response analysis and concurrent validity

OBJECTIVE

Childhood cancer survivors are at risk for neurocognitive impairment related to cancer diagnosis or treatment. This study refined and further validated the Childhood Cancer Survivor Study-Neurocognitive Questionnaire (CCSS-NCQ; Krull et al., 2008), a scale developed to screen for impairment in long-term survivors of childhood cancer.

METHOD

Items related to task efficiency, memory, organization, and emotional-regulation domains were examined using item response theory (IRT). Data were collected from 833 adult survivors of childhood cancer who completed self-report and direct neurocognitive testing for the St. Jude Lifetime Cohort Study. The revision process included: (a) content-validity mapping of items to domains, (b) constructing a revised CCSS-NCQ, (c) selecting items within specific domains using IRT, and (d) evaluating concordance between the revised CCSS-NCQ and direct neurocognitive assessment.

RESULTS

Using content and measurement properties, 32 items were retained (8 items in 4 domains). Items captured low to middle levels of neurocognitive concerns. The latent domain scores demonstrated poor convergent/divergent validity with the direct assessments. Adjusted ESs (ES; Cohen's d) for agreement between self-reported memory and direct memory assessment were moderate for total recall (ES = 0.66), long-term memory (ES = 0.63), and short-term memory (STM; ES = 0.55). ESs between self-rated task efficiency and direct assessment of attention were moderate for focused attention (ES = 0.70) and attention span (ES = 0.50), but small for sustained attention (ES = 0.36). Cranial radiation therapy and female gender were associated with lower self-reported neurocognitive function.

CONCLUSION

The revised CCSS-NCQ demonstrates adequate measurement properties for assessing day-to-day neurocognitive concerns in childhood cancer survivors, and adds useful information to direct assessment.

Hippocampal EUD in primarily irradiated glioblastoma patients

BACKGROUND

Radiation delivery for malignant brain tumors is gradually becoming more precise. Particularly the possibilities of sparing adjacent normal structures such as the hippocampus are increasing. To determine its radiation exposure more exactly, the equivalent uniform dose (EUD) of the hippocampus was compared with further treatment parameters. This way sparing options could be found.

METHODS

From the database of the University hospital of Munich 61 glioblastoma patients were selected who received primary radiotherapy in 2011. General data about the etiology, treatment course, survival of the patients and dose parameters were retrieved.

RESULTS

In a linear regression analysis the side of the tumor (left hippocampus: p < 0.001/right hippocampus: p = 0.009) and its temporal location (left hippocampus: p = 0.015/right hippocampus: p = 0.033) were identified as factors with a significant influence on the EUD of the respective hippocampus. Besides this, the size of the planning target volume (PTV) and the EUD of the hippocampus correlated significantly (p = 0.027; Pearson correlation = 0.291). The median PTV size of the tumor in the right hemisphere was 386.1 ml (range 131.2-910.7 ml), and in the left hemisphere 291.3 ml (range 146.0-588.9 ml) (Kruskal-Wallis test: p = 0.048). A dose quartile analysis showed that 31 patients had a high dose exposure of the hippocampus on one side while having a moderate dose exposure in the other side.

CONCLUSIONS

The radiation exposure of the respective hippocampus is dependent on the side where the tumor is located as well as on whether it is temporally located. The exposure of the contralateral hippocampus is further dependent on multiple additional factors - nevertheless a reasonable protection seems to be possible in about half of all cases.

No clinically relevant effect on cognitive outcomes after low-dose radiation to the infant brain: a population-based cohort study in Sweden

While the detrimental effects of cranial radiotherapy on the developing brain are well known, the effects on cognitive performance of low doses of ionizing radiation is less studied. We performed a population-based cohort study to determine whether low doses of ionizing radiation to the brain in infancy affects cognitive function later in life. Further we hypothesized that the dose to the hippocampus predicts cognitive late side effects better than the anterior or the posterior brain doses.

Material and methods

During 1950–1960 3860 boys were treated with radiation in Sweden for cutaneous hemangiomas before the age of 18 months. Of these, 3030 were analyzed for military test scores at the age of 18 years and 2559 for the highest obtained educational level.

Results

Logical, spatial and technical test scores were not affected by increasing irradiation doses. The verbal test scores displayed a significant trend for decreasing scores with increasing doses to the hippocampus (p = 0.005). However, the absolute mean difference between the zero dose and the highest dose category (median 680 mGy) was very small, only 0.64 stanine points, and the significance was dependent on the highest dose category, containing few subjects. The educational level was not affected by brain irradiation. Overall, the hippocampal dose was a better predictor of late cognitive side effects than the doses to the anterior or the posterior brain. In conclusion, there was no decrease in logical, spatial and technical verbal or global test scores after ionizing radiation doses up to 250 mGy, but a subtle decrease in verbal test scores if the highest dose category was included (median 680 mGy). However, the clinical relevance of this decline in the highest dose group is questionable, since we could not find any effect on the highest obtained educational level.

Critical combinations of radiation dose and volume predict intelligence quotient and academic achievement scores after craniospinal irradiation in children with medulloblastoma

PURPOSE

To prospectively follow children treated with craniospinal irradiation to determine critical combinations of radiation dose and volume that would predict for cognitive effects.

METHODS AND MATERIALS

Between 1996 and 2003, 58 patients (median age 8.14 years, range 3.99-20.11 years) with medulloblastoma received risk-adapted craniospinal irradiation followed by dose-intense chemotherapy and were followed longitudinally with multiple cognitive evaluations (through 5 years after treatment) that included intelligence quotient (estimated intelligence quotient, full-scale, verbal, and performance) and academic achievement (math, reading, spelling) tests. Craniospinal irradiation consisted of 23.4 Gy for average-risk patients (nonmetastatic) and 36-39.6 Gy for high-risk patients (metastatic or residual disease >1.5 cm(2)). The primary site was treated using conformal or intensity modulated radiation therapy using a 2-cm clinical target volume margin. The effect of clinical variables and radiation dose to different brain volumes were modeled to estimate cognitive scores after treatment.

RESULTS

A decline with time for all test scores was observed for the entire cohort. Sex, race, and cerebrospinal fluid shunt status had a significant impact on baseline scores. Age and mean radiation dose to specific brain volumes, including the temporal lobes and hippocampi, had a significant impact on longitudinal scores. Dichotomized dose distributions at 25 Gy, 35 Gy, 45 Gy, and 55 Gy were modeled to show the impact of the high-dose volume on longitudinal test scores. The 50% risk of a below-normal cognitive test score was calculated according to mean dose and dose intervals between 25 Gy and 55 Gy at 10-Gy increments according to brain volume and age.

CONCLUSIONS

The ability to predict cognitive outcomes in children with medulloblastoma using dose-effects models for different brain subvolumes will improve treatment planning, guide intervention, and help estimate the value of newer methods of irradiation.

Different reactions to irradiation in the juvenile and adult hippocampus

PURPOSE

Cranial radiotherapy is an important tool in the cure of primary brain tumors. Unfortunately, it is associated with late-appearing toxicity to the normal brain tissue, including cognitive impairment, particularly in children. The underlying mechanisms are not fully understood but involve changes in hippocampal neurogenesis. Recent studies report essentially different responses in the juvenile and the adult brain after irradiation, but this has never been verified in a comparative study.

MATERIALS AND METHODS

We subjected juvenile (9-day-old) and adult (6-month-old) male rats to a single dose of 6 Gray (Gy) whole brain irradiation and euthanized them 6 hours, 7 days or 4 weeks later. Hippocampal lysates were analyzed for caspase-3 activity (apoptosis) and the expression of cytokines, chemokines and growth factors. Four weeks after irradiation, the number of microglia (expressing ionized calcium-binding adapter molecule 1, Iba-1), activated microglia (expressing cluster of differentiation 68 [CD68]), bromodeoxyuridine (BrdU) incorporation and granule cell layer (GCL) volume were assessed.

RESULTS

The major findings were (i) higher baseline BrdU incorporation (cell proliferation) in juvenile than in adult controls, which explains the increased susceptibility to irradiation and higher level of acute cell death (caspase activity) in juvenile rats, leading to impaired growth and subsequently a smaller dentate gyrus volume 4 weeks after irradiation, (ii) more activated (CD68-positive) microglia in adult compared to juvenile rats, regardless of irradiation, and (iii) differently expressed cytokines and chemokines after cranial irradiation in the juvenile compared to the adult rat hippocampus, indicating a more pro-inflammatory response in adult brains.

CONCLUSION

We found essentially diverse irradiation reactions in the juvenile compared to the adult hippocampus, indicating different mechanisms involved in degeneration and regeneration after injury. Strategies to ameliorate the cognitive deficits after cranial radiotherapy should therefore likely be adapted to the developmental level of the brain.

Developing interventions for cancer-related cognitive dysfunction in childhood cancer survivors

Survivors of childhood cancer frequently experience cancer-related cognitive dysfunction, commonly months to years after treatment for pediatric brain tumors, acute lymphoblastic leukemia (ALL), or tumors involving the head and neck. Risk factors for cancer-related cognitive dysfunction include young age at diagnosis, treatment with cranial irradiation, use of parenteral or intrathecal methotrexate, female sex, and pre-existing comorbidities. Limiting use and reducing doses and volume of cranial irradiation while intensifying chemotherapy have improved survival and reduced the severity of cognitive dysfunction, especially in leukemia. Nonetheless, problems in core functional domains of attention, processing speed, working memory and visual-motor integration continue to compromise quality of life and performance. We review the epidemiology, pathophysiology and assessment of cancer-related cognitive dysfunction, the impact of treatment changes for prevention, and the broad strategies for educational and pharmacological interventions to remediate established cognitive dysfunction following childhood cancer. The increased years of life saved after childhood cancer warrants continued study toward the prevention and remediation of cancer-related cognitive dysfunction, using uniform assessments anchored in functional outcomes.

Sellar and parasellar lesions - clinical outcome in 61 children

OBJECTIVE

To evaluate clinical outcome in a 10-year consecutive series of children operated for sellar and parasellar tumors with special focus on neuropsychology and endocrinology.

PATIENTS AND METHODS

We analyzed 61 children (30 female) under 18 years of age (mean age 9.9, range 1 month-17 years) operated between 2000 and 2010. Medical records were evaluated retrospectively; postoperative histologic diagnoses included 20 craniopharyngiomas, 17 gliomas, 6 pituitary adenomas and 18 rare tumor entities.

RESULTS

Of 61 patients, 58 (95%) were still alive at last follow-up. Three patients died, all due to progression of malignant rhabdoid tumors. Postoperative clinical morbidity consisted of endocrinological (66%), visual (60.7%) and other neurological deficits (55.9%) after a mean follow-up of 44 months. When compared to all other tumor entities in this series, craniopharyngiomas were associated with high rates of gross-total resection (p=0.008), frequent progression of residual tumor (p=0.005) scotomas (p=0.013), persistent diabetes insipidus (p<0.001), and panhypopituitarism (p<0.001). Surgically treated gliomas showed higher rates of motor weakness (p=0.004), double vision (p<0.001), and milder forms of endocrinopathy (single hormone deficits, p=0.02). In general, deterioration in school performance was associated with multiple surgeries (p=0.018) and radiotherapy (p=0.021).

CONCLUSION

Excellent overall survival in these patients is possible, however malignant rhabdoid tumors have a poor prognosis. Aggressive treatment is associated with significant morbidity. Children operated for craniopharyngioma showed an expected high rate of endocrine deterioration, whereas glioma patients had higher incidences of motor weakness and double vision. The treating physicians should be well aware of all these considerable postoperative deficits, especially when facing interdisciplinary management decisions, and for the informed consent discussions with the patient and the parents.

Late toxicity following craniospinal radiation for early-stage medulloblastoma

BACKGROUND

The purpose of this study is to review late toxicity following craniospinal radiation for early-stage medulloblastoma.

MATERIAL AND METHODS

Between 1963 and 2008, 53 children with stage M0 (n = 50) or M1 (n = 3) medulloblastoma were treated at our institution. The median age at diagnosis was 7.1 years (range 1.2-18.5). The median craniospinal irradiation (CSI) dose was 28.8 Gy (range 21.8-38.4). The median total dose, including boost, was 54 Gy (range 42.4-64.8 Gy). Since 1963, the CSI dose has been incrementally lowered and the high-risk boost volume reduced. Twenty-one patients (40%) received chemotherapy in their initial management, including 12 who received concurrent chemotherapy. Late sequelae were evaluated by analyzing medical records and conducting phone interviews with surviving patients and/or care-takers. Complications were graded using the NCI Common Terminology Criteria for Adverse Events, version 4.0.

RESULTS

The median follow-up for all patients was 15.4 years (range 0.4-44.4) and for living patients it was 24 years (range 5.6-44.4). The overall survival, cause-specific survival, and progression-free survival rates at 10 years were 67%, 67%, and 71%, respectively. Sixteen patients (41% of patients who survived five years or more) developed grade 3 + toxicity; 15 of these 16 patients received a CSI dose > 23.4 Gy. The most common grade 3 + toxicities for long-term survivors are hearing impairment requiring intervention (20.5%) and cognitive impairment (18%) prohibiting independent living. Four patients developed secondary (non-skin) malignancies, including three meningiomas, one rhabdomyosarcoma, and one glioblastoma multiforme. Three patients (5.6%) died from treatment complications, including radionecrosis, severe cerebral edema, and fatal secondary malignancy.

CONCLUSION

Ongoing institutional and cooperative group efforts to minimize radiation exposure are justified given the high rate of serious toxicity observed in our long-term survivors. Follow-up through long-term multidisciplinary clinics is important and warranted for all patients exposed to radiotherapy in childhood.

Phase 2 trial of hypofractionated high-dose intensity modulated radiation therapy with concurrent and adjuvant temozolomide for newly diagnosed glioblastoma

PURPOSE/OBJECTIVES

To assess the effect and toxicity of hypofractionated high-dose intensity modulated radiation therapy (IMRT) with concurrent and adjuvant temozolomide (TMZ) in 46 patients with newly diagnosed glioblastoma multiforme (GBM).

METHODS AND MATERIALS

All patients underwent postsurgical hypofractionated high-dose IMRT. Three layered planning target volumes (PTVs) were contoured. PTV1 was the surgical cavity and residual tumor on T1-weighted magnetic resonance images with 5-mm margins, PTV2 was the area with 15-mm margins surrounding the PTV1, and PTV3 was the high-intensity area on fluid-attenuated inversion recovery images. Irradiation was performed in 8 fractions at total doses of 68, 40, and 32 Gy for PTV1, PTV2, and PTV3, respectively. Concurrent TMZ was given at 75 mg/m(2)/day for 42 consecutive days. Adjuvant TMZ was given at 150 to 200 mg/m(2)/day for 5 days every 28 days. Overall and progression-free survivals were evaluated.

RESULTS

No acute IMRT-related toxicity was observed. The dominant posttreatment failure pattern was dissemination. During a median follow-up time of 16.3 months (range, 4.3-80.8 months) for all patients and 23.7 months (range, 12.4-80.8 months) for living patients, the median overall survival was 20.0 months after treatment. Radiation necrosis was diagnosed in 20 patients and was observed not only in the high-dose field but also in the subventricular zone (SVZ). Necrosis in the SVZ was significantly correlated with prolonged survival (hazard ratio, 4.08; P=.007) but caused deterioration in the performance status of long-term survivors.

CONCLUSIONS

Hypofractionated high-dose IMRT with concurrent and adjuvant TMZ altered the dominant failure pattern from localized to disseminated and prolonged the survival of patients with GBM. Necrosis in the SVZ was associated with better patient survival, but the benefit of radiation to this area remains controversial.

Hippocampal sparing radiotherapy for pediatric medulloblastoma: impact of treatment margins and treatment technique

BACKGROUND

We investigated how varying the treatment margin and applying hippocampal sparing and proton therapy impact the risk of neurocognitive impairment in pediatric medulloblastoma patients compared with current standard 3D conformal radiotherapy.

METHODS

We included 17 pediatric medulloblastoma patients to represent the variability in tumor location relative to the hippocampal region. Treatment plans were generated using 3D conformal radiotherapy, hippocampal sparing intensity-modulated radiotherapy, and spot-scanned proton therapy, using 3 different treatment margins for the conformal tumor boost. Neurocognitive impairment risk was estimated based on dose-response models from pediatric CNS malignancy survivors and compared among different margins and treatment techniques.

RESULTS

Mean hippocampal dose and corresponding risk of cognitive impairment were decreased with decreasing treatment margins (P < .05). The largest risk reduction, however, was seen when applying hippocampal sparing proton therapy-the estimated risk of impaired task efficiency (95% confidence interval) was 92% (66%-98%), 81% (51%-95%), and 50% (30%-70%) for 3D conformal radiotherapy, intensity-modulated radiotherapy, and proton therapy, respectively, for the smallest boost margin and 98% (78%-100%), 90% (60%-98%), and 70% (39%-90%) if boosting the whole posterior fossa. Also, the distance between the closest point of the planning target volume and the center of the hippocampus can be used to predict mean hippocampal dose for a given treatment technique.

CONCLUSIONS

We estimate a considerable clinical benefit of hippocampal sparing radiotherapy. In choosing treatment margins, the tradeoff between margin size and risk of neurocognitive impairment quantified here should be considered.

Hippocampal-sparing radiotherapy: the new standard of care for World Health Organization grade II and III gliomas?

The neurocognitive effects of cranial radiotherapy in patients with gliomas are well-recognised and may be related to the dose delivered to the hippocampi. Intensity modulated radiotherapy (IMRT) is a radiotherapy technique that can be used to selectively spare the hippocampi without compromising the dose delivered to the tumour. This study aimed to evaluate if hippocampal-sparing IMRT is achievable in patients with World Health Organization (WHO) grade II and III gliomas. A retrospective review of consecutive patients with WHO grade II and III gliomas treated with IMRT at our institution between January 2009 and August 2012 was performed. Hippocampal-sparing was defined as a mean dose to at least one hippocampus of less than 30 Gy. The dose delivered to the tumour was never compromised to achieve the hippocampal dose constraint. Logistic regression analyses were performed to identify predictive factors for achieving hippocampal-sparing treatment. Eighteen patients were identified and hippocampal-sparing was achieved in 14 (78%). The median dose prescribed was 59.4 Gy in 33 fractions and 11 patients had WHO grade III gliomas. The mean dose to the contralateral hippocampus was 24.9 Gy. Planning target volumes less than 420.5 cm3 were more likely to enable hippocampal-sparing treatment to be given (hazard ratio 1.7, p=0.03) and there was a trend with oligodendrogliomas and anaplastic oligodendrogliomas. Hippocampal-sparing radiotherapy is feasible in patients with WHO grade II and III gliomas. Oncologic outcomes are yet to be assessed prospectively. The relationship between hippocampal dose and neurocognitive function in adults is currently under investigation.

Deficits in physical function among young childhood cancer survivors

PURPOSE

Childhood cancer survivors (CCSs) are at risk for physical disability. The aim of this investigation was to characterize and compare physical performance among CCSs and a group of siblings age < 18 years and determine if diagnosis, treatment, and physical activity levels were associated with lower performance scores.

METHODS

CCSs ≥ 5 years from diagnosis and a sibling comparison group were recruited and evaluated for strength, mobility, and fitness. Physical performance measures were compared in regression models between survivors and siblings by diagnosis and among survivors by treatment exposures and physical activity levels.

RESULTS

CCSs (n = 183; mean age ± standard deviation [SD], 13.5 ± 2.5 years; 53% male) scored lower than siblings (n = 147; mean age ± SD, 13.4 ± 2.4 years; 50% male) on lower-extremity strength testing, the timed up-and-go (TUG) test, and the 6-minute walk (6MW) test, despite reporting similar levels and types of habitual physical activity. The lowest scores were prevalent among survivors of CNS tumors and bone and soft tissue sarcomas on strength testing (score ± SD: CNS tumors, 76.5 ± 4.7; sarcoma 67.1 ± 7.2 v siblings, 87.3 ± 2.4 Newton-meters quadricep strength at 90° per second; P = .04 and .01, respectively) and among CNS tumor survivors on the TUG (score ± SD: 5.1 ± 0.1 v siblings, 4.4 ± 0.1 seconds; P < .001) and 6MW tests (score ± SD: 533.3 ± 15.6 v siblings, 594.1 ± 8.3 m; P < .001).

CONCLUSION

CCSs may have underlying physiologic deficits that interfere with function that cannot be completely overcome by participation in regular physical activity. These survivors may need referral for specialized exercise interventions in addition to usual counseling to remain physically active.

Antidepressant use among survivors of childhood, adolescent and young adult cancer: a report of the Childhood, Adolescent and Young Adult Cancer Survivor (CAYACS) Research Program

BACKGROUND

Although survivors of childhood, adolescent, and young adult (AYA) cancer are at risk for late psychological sequelae, it is unclear if they are more likely to be prescription antidepressant users than their peers.

PROCEDURE

All 5-year survivors of childhood or AYA cancer diagnosed before age 25 years in British Columbia from 1970 to 1995 were identified. Those with complete follow-up in the provincial health insurance registry from 2001 to 2004 were included (n = 2,389). A birth-cohort and gender-matched set of population controls 10 times the size of the survivor group was randomly selected (n = 23,890). All prescriptions filled between 2001 and 2004 were identified through linkage to the provincial prescription drug administrative database. Logistic regression analyses determined the impact of cancer survivorship on the likelihood of ever filling an antidepressant prescription.

RESULTS

After adjusting for sociodemographic factors, survivors of childhood and AYA cancer were more likely to have filled an antidepressant prescription compared to controls (OR 1.21, 95% CI 1.09-1.35). Cancer survivors had an increased likelihood of using all categories of antidepressants, and of using drugs from two or more antidepressant categories, compared to peers (OR 1.31, 95% CI 1.11-1.55 [≥2 antidepressant categories]). Treatment was not a significant predictor of antidepressant use. Female survivors, those in young adulthood and those more than 20 years post-treatment had increased antidepressant use.

CONCLUSIONS

Survivors of childhood and AYA cancer are more likely to fill antidepressant prescriptions compared to peer controls. This may indirectly reflect an increased underlying prevalence of mental health conditions among survivors.

Effect of cancer therapy on neural stem cells: implications for cognitive function

PURPOSE OF REVIEW

Modern cancer therapies have allowed for a dramatic increase in the survival rates in both children and adults. However, a frequent and unfortunate side-effect of cancer therapy is a long-term decline in neurocognitive function. Specifically, cranial radiation therapy markedly alters memory processes, while chemotherapeutic agents are correlated with deficits in attention, concentration, and speed of information processing. Here, we describe the putative cellular etiologies of cancer treatment-induced cognitive decline, with an emphasis on the role of neural stem and precursor cell dysfunction.

RECENT FINDINGS

New studies highlight the lasting effects of chemotherapy on memory, executive function, attention, and speed of information processing up to 20 years following chemotherapy. Cognitive decrements are associated with decreased white-matter integrity as well as alterations in stem cell function in humans and rodent models of cancer therapy. Genetic polymorphisms may underlie differential sensitivity of certain individuals to the neurological consequences of chemotherapy. Increasing data support the concept that disruption of normal neural stem and precursor cell function is an important causative factor for the cognitive deficits that result from cancer therapy in both children and adults.

SUMMARY

Further studies are needed to elucidate the role of chemotherapy on cell-intrinsic processes and cellular microenvironments. Further, the effects of the new generation of targeted molecular therapies on neural stem and progenitor cell function remains largely untested. Understanding the mechanisms behind cancer therapy-induced damage to neural stem and precursor cell populations will elucidate neuroprotective and cell replacement strategies aimed at preserving cognition after cancer therapy.

Association between radiation dose to neuronal progenitor cell niches and temporal lobes and performance on neuropsychological testing in children: a prospective study

BACKGROUND

Neurocognitive toxicity from radiation therapy (RT) for brain tumors may be related to damage to neural progenitor cells that reside in the subventricular zone and hippocampus. This prospective study examines the relationship between RT dose to neural progenitor cell niches, temporal lobes, and cerebrum and neurocognitive dysfunction following cranial irradiation.

METHODS

Standardized assessments of motor speed/dexterity, verbal memory, visual perception, vocabulary, and visuospatial working memory were conducted in 19 pediatric patients receiving cranial RT and 55 controls at baseline and 6, 15, and 27 months following completion of RT. Prescription doses ranged from 12 Gy to 59.4 Gy. Linear mixed effects regression model analyses were used to examine the relationships among neuropsychological performance, age, and radiation dose to the subventricular zone, hippocampus, temporal lobes, and cerebrum.

RESULTS

Performance on all neuropsychological tests, except vocabulary, was significantly reduced in patients relative to controls, particularly among younger children. Performance on motor speed/dexterity decreased with increasing dose to hippocampus (P < .05) and temporal lobes (P < .035). There was also a significant relationship between (i) reduced performance on verbal learning and increasing dose to the cerebrum (P = .022) and (ii) reduced performance on visual perception and increasing dose to the left temporal lobe (P = .038). There was no association between radiation dose to evaluated structures and performance on vocabulary or visuospatial working memory.

CONCLUSIONS

These prospective data demonstrate a significant association between increasing RT dose to hippocampus and temporal lobes and decline in neurocognitive skills following cranial irradiation. These findings have important implications for trials, including RTOG 0933 (hippocampal-sparing whole brain radiation therapy for brain metastases).

Parent-reported social outcomes after treatment for pediatric embryonal tumors: a prospective longitudinal study

PURPOSE

To examine longitudinal parent-reported social outcomes for children treated for pediatric embryonal brain tumors.

PATIENTS AND METHODS

Patients (N=220) were enrolled onto a multisite clinical treatment protocol. Parents completed the Child Behavior Checklist/6-18 at the time of their child's diagnosis and yearly thereafter. A generalized linear mixed effects model regression approach was used to examine longitudinal changes in parent ratings of social competence, social problems, and withdrawn/depressed behaviors with demographic and treatment factors as covariates.

RESULTS

During the 5-year period following diagnosis and treatment, few patients were reported to have clinically elevated scores on measures of social functioning. Mean scores differed significantly from population norms, yet remained within the average range. Several factors associated with unfavorable patterns of change in social functioning were identified. Patients with high-risk treatment status had a greater increase in parent-reported social problems (P=.001) and withdrawn/depressed behaviors (P=.01) over time compared with average-risk patients. Patients with posterior fossa syndrome had greater parent-reported social problems over time (P=.03). Female patients showed higher withdrawn/depressed scores over time compared with male patients (P<.001). Patient intelligence, age at diagnosis, and parent education level also contributed to parent report of social functioning.

CONCLUSION

Results of this study largely suggest positive social adjustment several years after diagnosis and treatment of a pediatric embryonal tumor. However, several factors, including treatment risk status and posterior fossa syndrome, may be important precursors of long-term social outcomes. Future research is needed to elucidate the trajectory of social functioning as these patients transition into adulthood.

Cerebral white matter integrity and executive function in adult survivors of childhood medulloblastoma

Survivors of pediatric medulloblastoma are at risk for neurocognitive dysfunction. Reduced white matter integrity has been correlated with lower intelligence in child survivors, yet associations between specific cognitive processes and white matter have not been examined in long-term adult survivors. Twenty adult survivors of medulloblastoma were randomly recruited from a larger institutional cohort of adult survivors of childhood cancer. Survivors underwent comprehensive neurocognitive evaluations and MRI. Data on brain volume and cortical thickness and diffusion tensor imaging were acquired, including measures of fractional anisotropy, apparent diffusion coefficient, and axial and radial diffusivity. Observed neurocognitive scores were compared with population norms and correlated to MRI indices. Survivors were, on average, 29 years of age and 18 years postdiagnosis. Mean full-scale intelligence quotient was nearly 1 SD below the normative mean (86.3 vs 100, P = .004). Seventy-five percent of survivors were impaired on at least one measure of executive function. Radial diffusivity in the frontal lobe of both hemispheres was correlated with shifting attention (left: r(s) = -0.67, P = .001; right: r(s) = -0.64, P = .002) and cognitive flexibility (left: r(s) = -0.56, P = .01; right: r(s) = -0.54, P = .01). Volume and cortical thickness were not correlated with neurocognitive function. Neurocognitive impairment was common and involved many domains. Reduced white matter integrity in multiple brain regions correlated with poorer performance on tasks of executive function. Future research integrating diffusion tensor imaging should be a priority to more rigorously evaluate long-term consequences of cancer treatment and to inform cognitive intervention trials in this high-risk population.

Antioxidant enzyme polymorphisms and neuropsychological outcomes in medulloblastoma survivors: a report from the Childhood Cancer Survivor Study

Psychological or neurocognitive impairment is often seen in medulloblastoma survivors after craniospinal radiation; however, significant variability in outcomes exists. This study investigated the role of antioxidant enzyme polymorphisms in moderating this outcome and hypothesized that patients who had polymorphisms associated with lower antioxidant enzyme function would have a higher occurrence of impairment. From the Childhood Cancer Survivor Study (CCSS) cohort, 109 medulloblastoma survivors and 143 siblings were identified who completed the CCSS Neurocognitive Questionnaire (NCQ) and the Brief Symptom Inventory-18 (BSI-18) and who provided buccal DNA samples. Real-time polymerase chain reaction (PCR) allelic discrimination was used for SOD2 (rs4880), GPX1 (rs1050450), and GSTP1 (rs1695 and rs1138272) genotyping and PCR for GSTM1 and GSTT1 gene deletions. Outcomes on NCQ and BSI-18 subscale scores were examined in association with genotypes and clinical factors, including age at diagnosis, sex, and radiation dose, using univariate and multivariate analysis of variance. Patients <7 years of age at diagnosis displayed more problems with task efficiency (P < .001) and fewer problems with somatic complaints (P = .004) than did patients ≥7 years of age. Female patients reported more organization problems than did male patients (P = .02). Patients with homozygous GSTM1 gene deletion reported higher anxiety (mean null genotype = 47.3 ± 9.2, non-null = 43.9 ± 7.8; P = .04), more depression (null = 51.0 ± 9.8, non-null = 47.0 ± 9.4; P = .03), and more global distress (null = 50.2 ± 9.7, non-null = 45.2 ± 9.9; P = .01). All associations for the GSTM1 polymorphism remained statistically significant in a multivariate model controlling for age, sex, and radiation dose. Homozygous GSTM1 gene deletion was consistently associated with greater psychological distress in medulloblastoma survivors across multiple domains, suggesting that this genotype may predispose patients for increased emotional late effects.