Pilocytic astrocytoma, a WHO Grade I tumor, is the most common pediatric brain tumor between 5 and 14 years of age and the second most common in children younger than 5 and older than 14. Although classical to the cerebellum and hypothalamic regions, it can also arise in the spinal cord 1).
The incidence of pediatric brain tumors varies among different countries. It ranges from 1.15 to 5.14 cases per 100,000 children, with the highest rates reported in the United States 2).
The incidence of congenital brain tumors (CBT) ranges from approximately 0.3 to 2.9 cases per 100,000 live births in different parts of the world 3) 4)
In a retrospective study of 128 children diagnosed with a CNS tumor under 5 years of age at a single center in the Division of Pediatric Neurosurgery, University Hospital Zurich between 1990 and 2019.
The median age at diagnosis was 1.81 years [IQR, 0.98-3.17]. The Median follow-up time of surviving patients was 8.39 years [range, 0.74-23.65]. The main tumor subtypes were pediatric low-grade glioma (36%), pediatric high-grade glioma (11%), ependymoma (16%), medulloblastoma (11%), other embryonal tumors (7%), germ cell tumors (3%), choroid plexus tumors (6%), and others (9%) 5).
The location of brain tumors in very young children differs from the posterior fossa predominance of older children. This is especially true in the first 6– 12 months of life, where supratentorial location is significantly more common.
Approximately 20% of pediatric intracranial tumors arise from the thalamus or brainstem, with an incidence rate of 5% and 15%, respectively.
Medulloblastoma is the most common malignant pediatric intracranial tumor.
Diffuse intrinsic pontine glioma account for 10% to 25% of pediatric intracranial tumors.
Wang et al.conducted a retrospective study on Pediatric Intracranial Tumor Epidemiology based on clinical data obtained from the Department of Neurosurgery, Xijing Hospital. After identifying the most prevalent tumor subtype, they identified new potential diagnostic biomarkers through bioinformatics analysis of the public database. All children (0-15 years) with brain tumors diagnosed histopathologically between 2010 and 2020 were reviewed retrospectively for age distribution, sex predilection, native location, tumor location, symptoms, and histological grade, and identified the most common tumor subtypes. Two datasets (GSE44971 and GSE44684) were downloaded from the Gene Expression Omnibus database, whereas the GSE44971 dataset was used to screen the differentially expressed genes between normal and tumor samples. Gene ontology, disease ontology, and gene set enrichment analysis enrichment analyses were performed to investigate the underlying mechanisms of differentially expressed genes in the tumor. Combined with methylation data in the GSE44684 dataset, they further analyzed the correlation between methylation and gene expression levels. Two algorithms, LASSO and SVM-RFE, were used to select the hub genes of the tumor. The diagnostic value of the hub genes was assessed using the receiver operating characteristic (ROC) curve. Finally, they further evaluated the relationship between the hub gene and the tumor microenvironment and immune gene sets. Overall, 650 children from 18 provinces in China were included in this study. The male-to-female ratio was 1.41:1, and the number of patients reached a peak in the 10-15-year-old group (41.4%). The most common symptoms encountered were headache and dizziness 250 (28.2%), and nausea and vomiting 228 (25.7%). The predominant location is supratentorial, with a supratentorial to an infratentorial ratio of 1.74:1. Low-grade tumors (WHO I/II) constituted 60.9% of all cases and were predominant in every age group. According to basic classification, the most common tumor subtype is pilocytic astrocytoma (PA). A total of 3264 differentially expressed genes were identified in the GSE44971 dataset, which is mainly involved in the process of neural signal transduction, immunity, and some diseases. Correlation analysis indicated that the expression of 45 differentially expressed genes was negatively correlated with promoter DNA methylation. Next, we acquired five hub genes (NCKAP1L, GPR37L1, CSPG4, PPFIA4, and C8orf46) from the 45 differentially expressed genes by intersecting the LASSO and SVM-RFE models. The ROC analysis revealed that the five hub genes had good diagnostic value for patients with PA (AUC > 0.99). Furthermore, the expression of NCKAP1L was negatively correlated with immune, stromal, and estimated scores, and positively correlated with immune gene sets. This study, based on the data analysis of intracranial tumors in children in a single center over the past 10 years, reflected the clinical and epidemiological characteristics of intracranial tumors in children in Northwest China to a certain extent. Pilocytic astrocytoma is considered the most common subtype of intracranial tumors in children. Through bioinformatics analysis, they suggested that NCKAP1L, GPR37L1, CSPG4, PPFIA4, and C8orf46 are potential biomarkers for the diagnosis of PA 6).