Neurological Complications of the Treatment of Pediatric Neoplastic Disorders

Childhood Cancer Survivors: An Overview of the Management of Late Effects

The collection of papers in this Special Issue entitled "Frailty in Pediatric and Young Adult Cancer Survivors: from bench to bedside" includes six interesting articles (five reviews and one single-center retrospective longitudinal cohort study) presented by expert researchers in the fields of oncology and pediatrics [...].

Exploring Trends in Neuromonitoring Use in a General Pediatric ICU: The Need for Standardized Guidance

Neuromonitoring has become more standardized in adult neurocritical care, but the utility of different neuromonitoring modalities in children remains debated. We aimed to describe the use of neuromonitoring in critically ill children with and without primary neurological diseases. We conducted a retrospective review of patients admitted to a 32-bed, non-cardiac PICU during a 12-month period. Neuro-imaging, electroencephalogram (EEG), cerebral oximetry (NIRS), automated pupillometry, transcranial doppler (TCD), intracranial pressure (ICP) monitoring, brain tissue oxygenation (PbtO2), primary diagnosis, and outcome were extracted. Neuromonitoring use by primary diagnosis and associations with outcome were observed. Of 1946 patients, 420 received neuro-imaging or neuromonitoring. Primary non-neurological diagnoses most frequently receiving neuromonitoring were respiratory, hematologic/oncologic, gastrointestinal/liver, and infectious/inflammatory. The most frequently used technologies among non-neurological diagnoses were neuro-imaging, EEG, pupillometry, and NIRS. In the multivariate analysis, pupillometry use was associated with mortality, and EEG, NIRS, and neuro-imaging use were associated with disability. Frequencies of TCD and PbtO2 use were too small for analysis. Neuromonitoring is prevalent among various diagnoses in the PICU, without clear benefit on outcomes when used in an ad hoc fashion. We need standard guidance around who, when, and how neuromonitoring should be applied to improve the care of critically ill children.

PASTEC - a prospective, single-center, randomized, cross-over trial of pure physical versus physical plus attentional training in children with cancer

Despite recent improvements in survival rates in children with cancer, long-term toxicities remain a major concern. Physical activity could reduce the impact of long-term sequelae, notably in neuropsychological and physical areas. We report of a randomized trial of pure physical versus physical/attentional training in pediatric oncology patients. Twenty-two patients aged 6-18 y.o. were included, irrespective of their clinical diagnosis or treatment status, stratified by age and randomized 1:1 into pure physical vs. physical/attentional activity arms, with a cross-over at study midpoint. Neurological, motor and neuropsychological assessments were performed at inclusion, start, crossover and end of the program. Feasibility, defined as > 80% patients attending > 80% of sessions, was the primary endpoint. Secondary outcomes were improvements in neuropsychological and motor performance tests. While 68% of patients attended more than 80% of sessions during the pre-crossover phase of the study, this dropped to 36% post-crossover. Our study therefore failed to meet our primary endpoint. Nonetheless, significant improvements in anxiety (p<0.001), emotional control (p = 0.04), organization skills (p = 0.03), as well as motor deficit scores (p = 0.04) were observed. We noted no significant difference between the pure physical and the physical/attentional training arms, or when analyzing subgroups by age or sequence of intervention. We conclude that physical activity has a positive impact on anxiety, emotional and organizational aspects as well as motor deficits. Attendance dropped during the course of the study and motivational interventions should be included in future studies or equivalent programs.Supplemental data for this article is available online at https://doi.org/10.1080/08880018.2021.1994677 .

Review: Neurological Complications From Therapies for Pediatric Brain Tumors

Surgery, chemotherapy and radiation have been the mainstay of pediatric brain tumor treatment over the past decades. Recently, new treatment modalities have emerged for the management of pediatric brain tumors. These therapies range from novel radiotherapy techniques and targeted immunotherapies to checkpoint inhibitors and T cell transfer therapies. These treatments are currently investigated with the goal of improving survival and decreasing morbidity. However, compared to traditional therapies, these novel modalities are not as well elucidated and similarly has the potential to cause significant short and long-term sequelae, impacting quality of life. Treatment complications are commonly mediated through direct drug toxicity or vascular, infectious, or autoimmune mechanisms, ranging from immune effector cell associated neurotoxicity syndrome with CART-cells to neuropathy with checkpoint inhibitors. Addressing treatment-induced complications is the focus of new trials, specifically improving neurocognitive outcomes. The aim of this review is to explore the pathophysiology underlying treatment related neurologic side effects, highlight associated complications, and describe the future direction of brain tumor protocols. Increasing awareness of these neurologic complications from novel therapies underscores the need for quality-of-life metrics and considerations in clinical trials to decrease associated treatment-induced morbidity.

Short and Long-Term Toxicity in Pediatric Cancer Treatment: Central Nervous System Damage

Simple Summary

The purpose of this review is to describe central nervous system side effects in the treatment of pediatric cancer patients. Unfortunately, we must consider that the scarce data in the literature does not allow us to expand on some issues, especially those related to innovative immunotherapy. We have described the major neurotoxicities arising with the various types of treatment to help specialists who approach these treatments recognize them early, prevent them, and treat them promptly.

Abstract

Neurotoxicity caused by traditional chemotherapy and radiotherapy is well known and widely described. New therapies, such as biologic therapy and immunotherapy, are associated with better outcomes in pediatric patients but are also associated with central and peripheral nervous system side effects. Nevertheless, central nervous system (CNS) toxicity is a significant source of morbidity in the treatment of cancer patients. Some CNS complications appear during treatment while others present months or even years later. Radiation, traditional cytotoxic chemotherapy, and novel biologic and targeted therapies have all been recognized to cause CNS side effects; additionally, the risks of neurotoxicity can increase with combination therapy. Symptoms and complications can be varied such as edema, seizures, fatigue, psychiatric disorders, and venous thromboembolism, all of which can seriously influence the quality of life. Neurologic complications were seen in 33% of children with non-CNS solid malign tumors. The effects on the CNS are disabling and often permanent with limited treatments, thus it is important that clinicians recognize the effects of cancer therapy on the CNS. Knowledge of these conditions can help the practitioner be more vigilant for signs and symptoms of potential neurological complications during the management of pediatric cancers. As early detection and more effective anticancer therapies extend the survival of cancer patients, treatment-related CNS toxicity becomes increasingly vital. This review highlights major neurotoxicities due to pediatric cancer treatments and new therapeutic strategies; CNS primary tumors, the most frequent solid tumors in childhood, are excluded because of their intrinsic neurological morbidity.

Improved prediction of postoperative paediatric cerebellar mutism syndrome using an artificial neural network

Background

Postoperative paediatric cerebellar mutism syndrome (pCMS) is a common but severe complication which may arise following the resection of posterior fossa tumours in children. Two previous studies have aimed to preoperatively predict pCMS, with varying results. In this work, we examine the generalisation of these models and determine if pCMS can be predicted more accurately using an artificial neural network (ANN).

Methods

An overview of reviews was performed to identify risk factors for pCMS, and a retrospective dataset collected as per these defined risk factors from children undergoing resection of primary posterior fossa tumours. The ANN was trained on this dataset and its performance evaluated in comparison to logistic regression and other predictive indices via analysis of receiver operator characteristic curves. Area under the curve (AUC) and accuracy were calculated and compared using a Wilcoxon signed rank test, with p&lt;0.05 considered statistically significant.

Results

204 children were included, of whom 80 developed pCMS. The performance of the ANN (AUC 0.949; accuracy 90.9%) exceeded that of logistic regression (p&lt;0.05) and both external models (p&lt;0.001).

Conclusion

Using an ANN, we show improved prediction of pCMS in comparison to previous models and conventional methods.

Characteristics and patterns of pediatric chemotherapy-induced peripheral neuropathy: A systematic review

This systematic review provides a high-quality synthesis of the empirical evidence regarding chemotherapy-induced peripheral neuropathy (CIPN) characteristics and patterns described in studies of children who received neurotoxic chemotherapy to treat cancer. PubMed, CINAHL, PsycINFO, and Embase were searched for articles published 2009 - 2019, yielding 861. Forty-two papers met the eligibility criteria, including 31 that described characteristics and patterns of vincristine-induced CIPN. Fifty-seven percent of articles were of low to moderate quality; measurement flaws were the most common limitations. The reported CIPN incidence varies widely (2.8%-100%) depending on risk factors (e.g., race) and the measurement approach. Incidence rates of sensory, motor, autonomic CIPN, and pain were 12-28%, 50-72%, 0.8-83% and 5.7-44%, respectively. The evidence suggests that sensory and motor neuropathy, pain, and functional deficits are common and can persist into adulthood. Caucasian race is a risk factor and, contrary to prior thinking, cumulative chemotherapy dosage alone does not predict CIPN severity. The influence of other risk factors is less clear, and studies to date have not explored potential interactions among race, genetics, age, sex, drug metabolism, and nutritional status, among other factors.

Intrathecal chemotherapy-associated cerebral vasospasm in children with hematologic malignancies

BACKGROUND

Mechanisms of chemotherapy-associated neurotoxicity are poorly understood, and therefore, prevention strategies have not been developed. We hypothesized that a subgroup of children receiving intrathecal cytarabine develops subclinical vasospasm, which may contribute to long-term neurocognitive sequelae of cancer.

METHODS

We used transcranial Doppler ultrasound to serially evaluate cerebral blood flow velocities in participants ≤25 years old receiving intrathecal cytarabine for hematologic malignancies.

RESULTS

Four of 18 participants (22%) met the criteria for subclinical vasospasm within 4 days of intrathecal cytarabine administration. The distribution of oncologic diagnoses differed between the vasospasm and non-vasospasm groups (p = 0.02). Acute myeloid leukemia was identified as a potential risk factor for vasospasm. Children with vasospasm were more likely to have received intravenous cytarabine (75% versus 0%, p = 0.01) and less likely to have received steroids (25% versus 100%, p = 0.01).

CONCLUSIONS

A subpopulation of children with hematologic malignancies develops subclinical vasospasm after intrathecal cytarabine treatment. Future research is needed to determine the long-term clinical consequences of cerebral vasospasm in this population.

IMPACT

A subset of children with hematologic malignancies who receive intrathecal cytarabine experience subclinical cerebral vasospasm, as measured by transcranial Doppler ultrasound. Of children receiving intrathecal cytarabine, those who develop cerebral vasospasm are more likely to have diagnosis of acute myeloid leukemia, more likely to receive concurrent intravenous cytarabine, and less likely to receive steroids as part of their chemotherapy regimen, as compared with children without vasospasm. Future research is needed to determine if vasospasm during chemotherapy is associated with higher rates of neurocognitive dysfunction, and if so, to focus on prevention of these long-term sequelae of childhood cancer.

COL1A1 polymorphism and neurological complications in pediatric acute lymphoblastic leukemia patients and their associations with altered bone mineral density

Background

Osteoporosis and neurological complications are consequences of acute lymphoblastic leukemia (ALL). Collagen type I alpha 1 gene (COL1A1) polymorphism is associated with osteoporosis. This study aimed to detect the COL1A1 polymorphism and the neurological complications in ALL patients and their association with decreased lumbar spine bone mineral density (BMDLS). This study included 100 pediatric ALL patients and 100 controls. All participants were subjected to laboratory assessment and assessment of BMDLS at the start of the study and 3 years later. COLIA1 genotyping was done once for all participants.

Results

At the start of the study, there was a significant decrease in osteocalcin (OC), alkaline phosphatase (ALP), and BMDLS levels in the patients. G/T variants and “T” alleles were significantly more detected in the patients (34% and 35% respectively); also, significant differences were detected between patients with polymorphism (G/T and T/T) and those without polymorphism (G/G) regarding OC, ALP, and BMDLS. After 3 years, significant decrement in BMDLS, OC, and ALP was detected in the patients. Twenty-four patients had neurological complications and seven patients had bone fractures. Those patients had significant decrement in BMDLS, OC, and ALP levels. As regards COL1A1 gene polymorphism, the GT and TT variants were significantly detected in fractured patients, while there was no significant difference regarding GT and TT variants in the patients with neurological complications. T allele, neurological complications, high-risk stratification, and age were significantly associated with decreased BMDLS. T allele was the most significant risk factor.

Conclusion

COLIA1 gene polymorphism, decreased BMDLS, and neurological complications were significantly detected in pediatric ALL patients. COLIA1 gene polymorphism is a significant risk factor for decreased BMDLS in pediatric ALL patients. There is no significant relation between COLIA1 gene polymorphism and the development of neurologic complications.

Neurological complications of pediatric cancer

Both the onset of various malignancies as well as the treatment of cancer can lead to neurologic symptoms which can be difficult to diagnose. In this review, we highlight the varied ways in which neurologic sequelae of cancer and its treatment manifest in children. Initial neurologic presentation may be secondary to mass effect or to immune-mediated paraneoplastic syndromes. Treatment effects on the nervous system may arise from surgery, chemotherapy, radiation, or bone marrow transplantation. In addition, the rapidly expanding field of immunotherapies for cancer has generated numerous new approaches to eradicating cancer including monoclonal antibodies, checkpoint inhibitors, and chimeric antigen receptor T cells (CAR-T cells), which have neurologic side effects mediated by immune responses that are also being recognized. Here we review common consult questions to the neurologist and our general approach to these scenarios including altered mental status, headaches, seizures, and sensorimotor complaints, considering the multifactorial nature of each.

Cancer and Tumor-Associated Childhood Stroke: Results From the International Pediatric Stroke Study

BACKGROUND

The prevalence of cancer among children with stroke is unknown. This study sought to evaluate cancer- and tumor-associated childhood ischemic stroke in a multinational pediatric stroke registry.

METHODS

Children aged 29 days to less than 19 years with arterial ischemic stroke or cerebral sinovenous thrombosis enrolled in the International Pediatric Stroke Study between January 2003 and June 2019 were included. Data including stroke treatment and recurrence were compared between subjects with and without cancer using Wilcoxon rank sum and chi-square tests.

RESULTS

Cancer or tumor was present in 99 of 2968 children (3.3%) with arterial ischemic stroke and 64 of 596 children (10.7%) with cerebral sinovenous thrombosis. Among children in whom cancer type was identified, 42 of 88 arterial ischemic stroke cases (48%) had brain tumors and 35 (40%) had hematologic malignancies; 45 of 58 cerebral sinovenous thrombosis cases (78%) had hematologic malignancies and eight (14%) had brain tumors. Of 54 cancer-associated arterial ischemic stroke cases with a known cause, 34 (63%) were due to arteriopathy and nine (17%) were due to cardioembolism. Of 46 cancer-associated cerebral sinovenous thrombosis cases with a known cause, 41 (89%) were related to chemotherapy-induced or other prothrombotic states. Children with cancer were less likely than children without cancer to receive antithrombotic therapy for arterial ischemic stroke (58% vs 80%, P = 0.007) and anticoagulation for cerebral sinovenous thrombosis (71% vs 87%, P = 0.046). Recurrent arterial ischemic stroke (5% vs 2%, P = 0.04) and cerebral sinovenous thrombosis (5% vs 1%, P = 0.006) were more common among children with cancer.

CONCLUSIONS

Cancer is an important risk factor for incident and recurrent childhood stroke. Stroke prevention strategies for children with cancer are needed.

Impact of SCID mouse gender on tumorigenicity, xenograft growth and drug-response in a large panel of orthotopic PDX models of pediatric brain tumors

Brain tumor is the leading cause of cancer related death in children. Clinically relevant animals are critical for new therapy development. To address the potential impact of animal gender on tumorigenicity rate, xenograft growth and in vivo drug responses, we retrospectively analyzed 99 of our established patient derived orthotopic xenograft mouse models (orthotopic PDX or PDOX). From 27 patient tumors, including 5 glioblastomas (GBMs), 11 medulloblastomas (MBs), 4 ependymomas (EPNs), 4 atypical teratoid/rhabdoid tumors (ATRTs) and 3 diffuse intrinsic pontine gliomas (DIPGs), that were directly implanted into matching locations in the brains of approximately equal numbers of male and female animals (n = 310) in age-matched (within 2-week age-difference) SCID mice, the tumor formation rate was 50.6 ± 21.5% in male and 52.7 ± 23.5% in female mice with animal survival times of 192.6 ± 31.7 days in male and 173.9 ± 34.5 days in female mice (P = 0.46) regardless of pathological diagnosis. Once established, PDOX tumors were serially subtransplanted for up to VII passage. Analysis of 1,595 mice from 59 PDOX models (18 GBMs, 18 MBs, 5 ATRTs, 6 EPNs, 7 DIPGs and 5 PENTs) during passage II and VII revealed similar tumor take rates of the 6 different tumor types between male (85.4 ± 15.5%) and female mice (84.7 ± 15.2%) (P = 0.74), and animal survival times were 96.7 ± 23.3 days in male mice and 99.7 ± 20 days in female (P = 0.25). A total of 284 mice from 7 GBM, 2 MB, 1 ATRT, 1 EPN, 2 DIPG and 1 PNET were treated with a series of standard and investigational drugs/compounds. The overall survival times were 106.9 ± 25.7 days in male mice, and 110.9 ± 31.8 days in female mice (P = 0.41), similar results were observed when different types/models were analyzed separately. In conclusion, our data demonstrated that the gender of SCID mice did not have a major impact on animal model development nor drug responses in vivo, and SCID mice of both genders are appropriate for use.

Hospital admission for neurologic disorders among 5-year survivors of noncentral nervous system tumors in childhood: A cohort study within the Adult Life after Childhood Cancer in Scandinavia study

Large, comprehensive studies of the risk for neurologic disorders among long-term survivors of noncentral nervous system (CNS) childhood cancers are lacking. Thus, the aim of our study was to assess the lifetime risk of Nordic non-CNS childhood cancer survivors for neurologic disorders. We identified 15,967 5-year survivors of non-CNS childhood cancer diagnosed in Denmark, Iceland, Finland and Sweden in 1943-2008, and 151,118 matched population comparison subjects. In-patient discharge diagnoses of neurologic disorders were used to calculate relative risks (RRs) and absolute excess risks (AERs). A neurologic disorder was diagnosed in 755 of the survivors while 370 were expected, yielding a RR of 2.0 (95% confidence interval (CI) 1.9-2.2). The highest risks were found among survivors of neuroblastoma (4.1; 95% CI 3.2-5.3) and leukemia (2.8; 95% CI 2.4-3.2). The AER decreased from 331 (278-383) excess neurologic disorders per 100,000 person-years 5-9 years after diagnosis to 82 (46-118) ≥ 20 years after diagnosis. Epilepsy was the most common diagnosis (n = 229, 1.4% of all survivors), and significantly increased risks were seen among survivors of eight out of 12 types of childhood cancer. Survivors of neuroblastoma had remarkably high risks (RR ≥ 10) for hospitalization for paralytic syndromes and hydrocephalus, while survivors of leukemia had additional high risks for dementia and encephalopathy. In conclusion, survivors of non-CNS childhood cancer are at high risk for neurologic disorders, especially within the first decade after diagnosis. Therefore, intensive follow-up to identify those who require close management is needed.

Late effects of pediatric brain tumors

PURPOSE OF REVIEW

Adverse late effects of pediatric brain tumors can be numerous and complex and potentially alter the life trajectories of survivors in a multitude of ways. We review these inter-related late effects that compromise neurocognitive function, general health, social and psychological adjustment, and overall adaptive and vocational outcomes, and threaten to undermine the ability of survivors to transition independently into adulthood and effectively manage their care. Intervention/prevention strategies and advances in treatment that may reduce such late effects are discussed.

RECENT FINDINGS

Studies of neuropsychological late effects have revealed specific deficits in core cognitive functions of attention, working memory and processing speed, with many survivors demonstrating decline in working memory and processing speed over time, irrespective of tumor type or treatment. This in turn affects the ongoing development of higher order neurocognitive skills. Research also highlights the increasing burden of health-related, neuropsychological and psychosocial late effects into adulthood and impact across life outcomes.

SUMMARY

Pediatric brain tumor survivors require coordinated interdisciplinary care, ongoing evaluation and management of late effects, and timely interventions focused on mitigating the impact of late effects. The transition to adulthood can be especially vulnerable and addressing barriers to care is of paramount importance.

Saving normal tissues - a goal for the ages

Almost since the earliest utilization of ionizing radiation, many within the radiation community have worked toward either preventing (i.e. protecting) normal tissues from unwanted radiation injury or rescuing them from the downstream consequences of exposure. However, despite over a century of such investigations, only incremental gains have been made toward this goal and, with certainty, no outright panacea having been found. In celebration of the 60th anniversary of the International Journal of Radiation Biology and to chronicle the efforts that have been made to date, we undertook a non-rigorous survey of the articles published by normal tissue researchers in this area, using those that have appeared in the aforementioned journal as a road map. Three 'snapshots' of publications on normal tissue countermeasures were taken: the earliest (1959-1963) and most recent (2013-2018) 5-year of issues, as well as a 5-year intermediate span (1987-1991). Limiting the survey solely to articles appearing within International Journal of Radiation Biology likely reduced the number of translational studies interrogated given the basic science tenor of this particular publication. In addition, by taking 'snapshots' rather than considering the entire breadth of the journal's history in this field, important papers that were published during the interim periods were omitted, for which we apologize. Nonetheless, since the journal's inception, we observed that, during the chosen periods, the majority of studies undertaken in the field of normal tissue countermeasures, whether investigating radiation protectants, mitigators or treatments, have focused on agents that interfere with the physical, chemical and/or biological effects known to occur during the acute period following whole body/high single dose exposures. This relatively narrow approach to the reduction of normal tissue effects, especially those that can take months, if not years, to develop, seems to contradict our growing understanding of the progressive complexities of the microenvironmental disruption that follows the initial radiation injury. Given the analytical tools now at our disposal and the enormous benefits that may be reaped in terms of improving patient outcomes, as well as the potential for offering countermeasures to those affected by accidental or mass casualty exposures, it appears time to broaden our approaches to developing normal tissue countermeasures. We have no doubt that the contributors and readership of the International Journal of Radiation Biology will continue to contribute to this effort for the foreseeable future.