Estimated IQ Systematically Underestimates Neurocognitive Sequelae in Irradiated Pediatric Brain Tumor Survivors

Survivors of infant atypical teratoid/rhabdoid tumors present with severely impaired cognitive functions especially for fluid intelligence and visual processing: data from the German brain tumor studies

BACKGROUND

The contribution of tumor type, multimodal treatment, and other patient-related factors upon long-term cognitive sequelae in infant brain tumor survivors remains undefined. We add our retrospective analysis of neuropsychological and quality of survival (QoS) outcome data of survivors of atypical teratoid/rhabdoid tumors (ATRT) and extracranial malignant rhabdoid tumors of the soft tissues (eMRT) and kidneys (RTK) treated within the same framework. Neuropsychological data from children with ATRT were compared to data from children with non-irradiated low-grade glioma (LGG).

PATIENTS AND METHODS

Following surgery, patients (0-36 months at diagnosis) had received radio-chemotherapy (up to 54 Gy; ATRT: n = 13; eMRT/RTK: n = 7), chemotherapy only (LGG: n = 4; eMRT/RTK: n = 1) or had been observed (LGG: n = 11). Neuropsychological evaluation employing comparable tests was performed at median 6.8 years (ATRT), 6.6 years (eMRT/RTK), and 5.2 years (LGG) post diagnosis.

RESULTS

We detected sequelae in various domains for all tumor types. Group comparison showed impairments, specifically in fluid intelligence (p = .041; d = 1.11) and visual processing (p = .001; d = 2.09) in ATRT patients when compared to LGG patients. Results for psychomotor speed and attention abilities were significantly below the norm for both groups (p < .001-.019; d = 0.79-1.90). Diagnosis predicted impairments of cognitive outcome, while sex- and age-related variables did not. QoS outcome for all rhabdoid patients displayed impairments mainly in social (p = .008; d = 0.74) and school functioning (p = .048; d = 0.67), as well as lower overall scores in psychosocial functioning (p = .023; d = 0.78) and quality of life (p = .006; d = 0.79) compared to healthy controls.

CONCLUSION

Survivors of infant ATRT experience various late effects in cognition and QoS following multimodal treatment, while infant LGG patients without radiotherapy demonstrated comparable impairments in psychomotor and attention abilities. Early onset and multimodal treatment of rhabdoid tumors require close monitoring of neuropsychological and QoS sequelae.

Oxygen supplementation in anesthesia can block FLASH effect and anti-tumor immunity in conventional proton therapy

BACKGROUND

Radiation-induced neurocognitive dysfunction is a major adverse effect of brain radiation therapy and has specific relevance in pediatric oncology, where serious cognitive deficits have been reported in survivors of pediatric brain tumors. Moreover, many pediatric patients receive proton therapy under general anesthesia or sedation to guarantee precise ballistics with a high oxygen content for safety. The present study addresses the relevant question of the potential effect of supplemental oxygen administered during anesthesia on normal tissue toxicity and investigates the anti-tumor immune response generated following conventional and FLASH proton therapy.

METHODS

Rats (Fischer 344) were cranially irradiated with a single high dose of proton therapy (15 Gy or 25 Gy) using FLASH dose rate proton irradiation (257 ± 2 Gy/s) or conventional dose rate proton irradiation (4 ± 0.02 Gy/s), and the toxicities in the normal tissue were examined by histological, cytometric and behavioral analysis. Glioblastoma-bearing rats were irradiated in the same manner and tumor-infiltrating leukocytes were quantified by flow cytometry.

RESULTS

Our findings indicate that supplemental oxygen has an adverse impact on both functional and anatomical evaluations of normal brain following conventional and FLASH proton therapy. In addition, oxygen supplementation in anesthesia is particularly detrimental for anti-tumor immune response by preventing a strong immune cell infiltration into tumoral tissues following conventional proton therapy.

CONCLUSIONS

These results demonstrate the need to further optimize anesthesia protocols used in radiotherapy with the goal of preserving normal tissues and achieving tumor control, specifically in combination with immunotherapy agents.

Frequency and characterization of cognitive impairments in patients diagnosed with paediatric central nervous system tumours: a systematic review

Background

This systematic review has been conducted with the aim of characterizing cognitive deficits and analyzing their frequency in survivors of paediatric Central Nervous System tumours.

Materials and methods

All literature published up to January 2023 was retrieved searching the databases "PubMed", "Cochrane", "APA PsycInfo" and "CINAHL". The following set of pre-defined inclusion criteria were then individually applied to the selected articles in their full-text version: i) Retrospective/prospective longitudinal observational studies including only patients diagnosed with primary cerebral tumours at ≤ 21 years (range 0-21); ii) Studies including patients evaluated for neuro-cognitive and neuro-psychological deficits from their diagnosis and/or from anti-tumoral therapies; iii) Studies reporting standardized tests evaluating patients' neuro-cognitive and neuro-psychological performances; iv) Patients with follow-ups ≥ 2 years from the end of their anti-tumoral therapies; v) Studies reporting frequencies of cognitive deficits.

Results

39 studies were included in the analysis. Of these, 35 assessed intellectual functioning, 30 examined memory domains, 24 assessed executive functions, 22 assessed attention, 16 examined visuo-spatial skills, and 15 explored language. A total of 34 studies assessed more than one cognitive function, only 5 studies limited their analysis on a single cognitive domain. Attention impairments were the most recurrent in this population, with a mean frequency of 52.3% after a median period post-treatment of 11.5 years. The other cognitive functions investigated in the studies showed a similar frequency of impairments, with executive functions, language, visuospatial skills and memory deficits occurring in about 40% of survivors after a similar post-treatment period. Longitudinal studies included in the systematic review showed a frequent decline over time of intellectual functioning.

Conclusions

Survivors of paediatric Central Nervous System tumours experience cognitive sequelae characterized by significant impairments in the attention domain (52.3%), but also in the other cognitive functions. Future studies in this research field need to implement more cognitive interventions and effective, but less neurotoxic, tumour therapies to preserve or improve neurocognitive functioning and quality of life of this population.

The impact of socioeconomic status (SES) on cognitive outcomes following radiotherapy for pediatric brain tumors: a prospective, longitudinal trial

BACKGROUND

Socioeconomic status (SES) is a determinant of cognitive and academic functioning among healthy and ill children; however, few pediatric oncology studies examine SES and long-term cognitive functioning. The current study systematically investigated SES as a predictor of cognitive outcomes among children treated for localized brain tumors (BT) with photon radiation therapy (RT).

METHODS

248 children treated on a prospective, longitudinal, phase II trial of conformal RT (54-59.4 Gy) for ependymoma, low-grade glioma, or craniopharyngioma were monitored serially with cognitive assessments (intelligence quotient [IQ], reading, math, attention, adaptive function) for 10 years (2209 observations, median age at RT = 6.6 years, 48% male, 80% Caucasian). SES was derived from the Barratt Simplified Measure of Social Status, which incorporates parental occupation, education, and marital status.

RESULTS

Overall, SES scores fell in the low range (Barratt median = 37). At pre-RT baseline, linear mixed models revealed significant associations between SES and IQ, reading, math, attention, and adaptive function, with higher SES associated with better performance (P < .005). SES predicted change over time in IQ, reading, and math; higher SES was associated with less decline (P < .001). Accounting for sex and age at RT, SES remained predictive of IQ, reading, and math. Analysis of variance revealed a greater relative contribution of SES than sex or age at RT to reading and math.

CONCLUSIONS

SES represents a novel predictor of cognitive performance before and after RT for pediatric BT. These findings have broad implications as high SES represents a protective factor. Developing interventions to mitigate the effects of low SES is warranted.

Normal tissue tolerance amongst paediatric brain tumour patients- current evidence in proton radiotherapy

BACKGROUND

Proton radiotherapy (PT) is used increasingly for paediatric brain cancer patients. However, as demonstrated here, the knowledge on normal tissue dose constraints, to minimize side-effects, for this cohort is limited.

METHODS

A search strategy was systematically conducted on MEDLINE® database. 65 papers were evaluated ranging from 2013 to 2021.

RESULTS

Large variations in normal tissue tolerance and toxicity reporting across PT studies makes estimation of normal tissue dose constraints difficult, with the potential for significant late effects to go unmeasured. Mean dose delivered to the pituitary gland varies from 20 to 30 Gy across literature. Similarly, the hypothalamic dose delivery ranges from 20 to 54.6 Gy for paediatric patients.

CONCLUSION

There is a significant lack of radiobiological data for paediatric brain cancer patients undergoing proton therapy, often using data from x-ray radiotherapy and adult populations. The way forward is through standardisation of reporting in order to validate relevant dose constraints.

Predictors of Cognitive Performance Among Infants Treated for Brain Tumors: Findings From a Multisite, Prospective, Longitudinal Trial

PURPOSE

Infants treated for CNS malignancies experience a significantly poorer response to treatment and are particularly at risk for neuropsychological deficits. The literature is limited and inconsistent regarding cognitive outcomes among this group. We investigated predictors of cognitive outcomes in children treated for brain tumors during infancy as part of a large, prospective, multisite, longitudinal trial.

PATIENTS AND METHODS

One hundred thirty-nine infants with a newly diagnosed CNS tumor were treated with chemotherapy, with or without focal proton or photon radiation therapy (RT). Cognitive assessments were conducted at baseline, 6 months, 1 year, and then annually for 5 years. The median length of follow-up was 816 days (26.8 months). Neurocognitive testing included assessment of intellectual functioning (intellectual quotient [IQ]), parent ratings of executive functioning and emotional and behavioral functioning, and socioeconomic status.

RESULTS

At baseline, IQ, parent-reported working memory, and parent-reported adaptive functioning were worse than normative expectations. Baseline cognitive difficulties were associated with younger age at diagnosis and lower socioeconomic status. Linear mixed models did not demonstrate a decline in IQ over time. There were increased parent-reported attention and executive problems over time. Increased concerns were related to supratentorial tumor location and CSF diversion. There were no differences in cognitive outcomes based on treatment exposure (chemotherapy-only v chemotherapy with RT and proton v photon focal RT).

CONCLUSION

Even before adjuvant therapy, young children with brain tumors experience cognitive difficulties that can affect quality of life. Changes in cognitive functioning over time were dependent on tumor location and surgical factors rather than adjuvant therapy. These findings may serve to guide treatment planning and indicate targets for cognitive monitoring and intervention.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Predictors of cognitive function in pediatric brain tumor patients: Pre-surgery through 24-month follow-up

The aim of this study was to examine the feasibility of cognitive assessment from pre-surgery through 2-year follow-up in a sample of pediatric brain tumor (BT) patients. We sought to investigate cognitive function over the course of diagnosis and treatment, and as a function of presenting problems, tumor location, treatment type, and tumor severity. Using a prospective, longitudinal design, standardized IQ measures were administered to pediatric BT patients (ages 6-16) prior to surgery (n = 25), 6 months post-diagnosis (n = 24), and 24 months post-diagnosis (n = 23). Group differences emerged based on tumor severity and treatment type at multiple time points, including prior to surgical intervention; children with high grade tumors performed more poorly than children with low grade tumors, and children receiving surgery plus adjuvant therapy performed more poorly than children who received surgery only. When considered together, an analysis of covariance demonstrated that tumor grade significantly accounted for variability in cognitive functioning, while treatment type did not. Although there is overlap clinically between tumor severity and treatment received, results suggest that tumor severity is an important factor contributing to variability in cognitive functioning and should also be considered when monitoring risk for cognitive deficits in children diagnosed with BT.

Trajectories of psychosocial and cognitive functioning in pediatric patients with brain tumors treated with radiation therapy

BACKGROUND

Pediatric patients with brain tumors who are treated with radiation therapy (RT) are at risk for neurocognitive and psychosocial late effects. Research to date has primarily examined these outcomes at a group level and in isolation. Advanced statistical techniques allow for person-centered analyses, as well as examination of relationships between domain-specific trajectories.

METHODS

Patients with brain tumors (craniopharyngioma, ependymoma, low-grade astrocytoma, high-grade astrocytoma) were enrolled on a phase II clinical trial of RT. Three hundred and fifty patients completed serial neurocognitive assessments as part of their treatment monitoring, including pre-RT baseline, 6 months post-RT, and then yearly for 5 years. This secondary analysis focused on outcomes of cognition (estimated IQ, parent-reported attention problems) and psychosocial effects (parent-reported socialization and social problems) post-RT.

RESULTS

Latent growth curve modeling indicated that estimated IQ and socialization were best served by quadratic models, while attention and social problems were best served by linear models. Growth mixture modeling indicated 3-class models were the best fit for IQ and socialization, and 2-class models for attention and social problems. Baseline IQ and socialization scores were associated, but there was no association over time. Young age at diagnosis and pre-RT treatments (surgery, chemotherapy) were associated with class membership.

CONCLUSIONS

Person-centered statistical analyses provide rich information regarding the variability in neurocognitive and psychosocial functioning following RT for pediatric brain tumor. While many patients do well over time, a subset are exhibiting significant cognitive and/or psychosocial deficits. Class membership was associated with some medical factors (eg, pre-radiation surgery/chemotherapy, age at diagnosis, shunted hydrocephalus).

Neuropsychological functioning in survivors of childhood medulloblastoma/CNS-PNET: The role of secondary medical complications

OBJECTIVE

To investigate the long-term cognitive consequences of malignant pediatric brain tumor and its treatment, and factors explaining variability in cognitive functioning among survivors. Method: A geographical cohort of survivors of pediatric medulloblastoma (MB) and supratentorial primitive neuroectodermal tumor (CNS-PNET), treated between 1974 and 2013, was invited to participate. Of the 63 surviving patients, 50 (79%) consented to participation. The participants were tested with a battery of neuropsychological tests covering a wide age range. Verbal cognition, nonverbal cognition, processing speed, attention, memory, executive functioning, and manual dexterity were assessed. The participants were between 5:5 and 51:11 years of age at time of assessment. Assessments took place on average 19 years after primary tumor resective surgery. Results: One participant had a severe intellectual disability. For the rest, IQ varied from 52 to 125, with a mean score of 88.0 (SD 19.7). Twenty-eight (56%) of the participants had full-scale IQ scores in the age-average range or above. Gender, age at operation, time since operation, the presence of secondary medical complications, and treatment variables explained 46% of the variability in IQ scores, F(4,44) =  9.5, p<.001. The presence of endocrine insufficiency in combination with either epilepsy and/or hydrocephalus was associated with lowered IQ, lowered processing speed, and memory impairments. Conclusion: Patients treated for childhood MB and CNS-PNET have a lifelong risk of medical sequelae, including impaired cognitive functioning. This study adds to the literature by demonstrating the importance of following neuropsychological functioning closely, especially processing speed, learning, and memory, in survivors who have multiple secondary medical complications.

The role of proton therapy in pediatric malignancies: Recent advances and future directions

Proton radiotherapy has promised an advantage in safely treating pediatric malignancies with an increased capability to spare normal tissues, reducing the risk of both acute and late toxicity. The past decade has seen the proliferation of more than 30 proton facilities in the United States, with increased capacity to provide access to approximately 3,000 children per year who will require radiotherapy for their disease. We provide a review of the initial efforts to describe outcomes after proton therapy across the common pediatric disease sites. We discuss the main attempts to assess comparative efficacy between proton and photon radiotherapy concerning toxicity. We also discuss recent efforts of multi-institutional registries aimed at accelerating research to better define the optimal treatment paradigm for children requiring radiotherapy for cure.

Cognitive and Psychosocial Development in Young Children with Brain Tumors: Observations from a Clinical Sample

Survivors of pediatric brain tumor (BT) are known to be at risk for developing cognitive and psychosocial late effects. Young age at treatment (≤6 years) is typically considered to put patients at increased risk. However, there is limited research specifically exploring functioning in these young patients. Cognitive and psychosocial data were retrospectively abstracted from medical charts for 79 young patients (54.4% male) treated for BT with a variety of treatment modalities (e.g., surgery, radiation therapy, chemotherapy). Children were clinically assessed at 4.52 years of age (range = 1.48-5.98) and most were off-therapy (74.4%). Mean performances on developmental (68.3 ± 10.02), cognitive (88.09 ± 18.38), and pre-academic (86.84 ± 19.75) measures were all below average. Parent report of adaptive functioning was also below average (82.10 ± 16.21), but psychosocial functioning was generally within normal limits. Most patients had impaired functioning (scores <10th percentile) in at least one domain assessed. Exploratory analyses revealed that many patients (27.3-60.6%) exhibited a significant discrepancy between domains of cognitive functioning (e.g., verbal and spatial). Young children treated for BT experienced high rates of impairment in cognitive, pre-academic, and adaptive domains. Future work is needed to focus on serial longitudinal assessment of these young patients, as well as dedicated intervention and prevention efforts.

Cranial irradiation in juvenile mice leads to early and sustained defects in the stem and progenitor cell pools and late cognitive impairments

Cranial irradiation is used in combination with other therapies as a treatment for brain tumours and is thought to contribute to long-term cognitive deficits. Several rodent models have demonstrated that these cognitive deficits may be correlated with damage to neural progenitor cells in the subventricular zone (SVZ) and dentate gyrus (DG), the two neurogenic niches of the brain. Studies in rodent models typically assess the proliferating progenitor population, but rarely investigate the effect of cranial irradiation on the neural stem cell pool. Further, few studies evaluate the effects in juveniles, an age when children typically receive this treatment. Herein, we examine the cellular and behavioural effects of juvenile cranial irradiation on stem and progenitor populations in the two neurogenic regions of the brain and assess cognitive outcomes. We found regionally distinct effects of cranial irradiation in the juvenile brain. In the SVZ, we observed a defect in the stem cell pool and a concomitant decrease in proliferating cells that were maintained for at least one week. In the DG, a similar defect in the stem cell pool and proliferating cells was observed and persisted in the stem cell population. Finally, we demonstrated that cranial irradiation resulted in late cognitive deficits. This study demonstrates that juvenile cranial irradiation leads to regionally distinct defects in the stem and progenitor populations, and late cognitive deficits, which may be important factors in determining therapeutic targets and timing of interventions following cranial irradiation.

Radiation doses to brain substructures associated with cognition in radiotherapy of pediatric brain tumors

Background: Several brain substructures associated with cognition (BSCs) are located close to typical pediatric brain tumors. Pediatric patients therefore have considerable risks of neurocognitive impairment after brain radiotherapy. In this study, we investigated the radiation doses received by BSCs for three common locations of pediatric brain tumor entities. Material and methods: For ten patients in each group [posterior fossa ependymoma (PFE), craniopharyngioma (CP), and hemispheric ependymoma (HE)], the cumulative fraction of BSCs volumes receiving various dose levels were analyzed. We subsequently explored the differences in dose pattern between the three groups and used available dose response models from the literature to estimate treatment-induced intelligence quotient (IQ) decline. Results: Doses to BSCs were found to differ considerably between the groups, depending on their position relative to the tumor. Large inter-patient variations were observed in the ipsilateral structures of the HE groups, and at low doses for all three groups. IQ decline estimates differed depending on the model applied, presenting larger variations in the HE group. Conclusion: While there were notable differences in the dose patterns between the groups, the extent of estimated IQ decline depended more on the model applied. This inter-model variability should be considered in dose-effect assessments on cognitive outcomes of pediatric patients.

Cognitive and Adaptive Outcomes After Proton Radiation for Pediatric Patients With Brain Tumors

PURPOSE

Radiation therapy is integral in treatment of pediatric brain tumors, but it is associated with negative long-term sequelae. Proton beam radiation therapy (PRT), which enables better focusing of radiation on tumors, may entail fewer sequelae. This prospective study examined cognitive and adaptive functioning in children and young adults treated with PRT.

METHODS AND MATERIALS

A total of 155 patients were assessed using age-appropriate measures for cognitive and adaptive functioning at start of or during PRT (baseline) and at follow-up. Mean age at baseline was 8.9 years; mean follow-up interval was 3.6 years. Diagnoses included medulloblastoma, craniopharyngioma, ependymoma, glial tumors, germ cell tumors, and others. The sample was divided by age at baseline (<6 years [N = 57, or 37%] and ≥6 years [N = 98, or 63%]) and by PRT field (craniospinal irradiation [CSI; 39%] and focal irradiation [61%]).

RESULTS

Scores for mean intelligence quotient (IQ) and adaptive functioning skills were in the average range at baseline and follow-up. Overall, mean IQ scores declined from 105.4 to 102.5 (P = .005); however, only the younger CSI group showed significant decline. Patients receiving CSI, regardless of age, appeared particularly vulnerable in IQ, processing speed, and working memory. Adaptive skills were stable across the 4 age-by-treatment field groups.

CONCLUSIONS

At a mean of 3.6 years after PRT, IQ declined slightly for the group, largely because of significant IQ decline in younger patients treated with CSI. No significant change was seen in patients <6 years treated with focal PRT or in older patients. Adaptive skills remained stable across age and treatment type.