Pediatric CNS tumors: Overview and treatment paradigms

Central nervous system (CNS) tumors represent the most common solid tumors occurring in children, with gliomas, medulloblastomas and ependymomas being the most frequently diagnosed. The most recent 2021 World Health Organization (WHO) Classification of Tumors of the CNS (CNS5) has integrated molecular genetics with traditional histopathology leading to more accurate diagnosis and risk stratification/prognostication with subsequent development of personalized treatment paradigms. Pediatric gliomas are traditionally subdivided into low-grade (pLGG) or high-grade gliomas (pHGG). pLGG tend to have excellent overall survival, however, the disease course maybe characterized by multiple recurrences resulting in significant morbidity. Surgical resection is standard with medical therapy (chemotherapy or oral molecular targeted therapy) reserved in the event of radiographic/symptomatic progression. pHGG have poor overall survival despite intensive multimodality therapy. Ependymomas occur in the infratentorial and supratentorial brain as well as in the spine, with the standard treatment including maximal safe resection with involved field radiation therapy that is curative in two-thirds of patients overall. Medulloblastomas are the most common malignant embryonal CNS tumor arising in the cerebellum and are biologically heterogeneous. Given the risk of CSF dissemination, medulloblastomas require surgery, craniospinal radiation as well as multi agent chemotherapy, an approach that is curative in the majority of patients with non-metastatic disease. The field of pediatric neuro-oncology has made robust strides in the past few decades and the role of molecular diagnostics has continued to improve our understanding of pediatric tumor biology and offer more personalized treatment paradigms.