Tumors: Brain

Abstract

Primary brain tumors are thought to originate from neuroglial progenitor cells of the central nervous system (CNS). The current World Health Organization (WHO) classification for brain tumors was published in 2016 (Louis et al. 2016) and uses morphological characteristics based on presumed origin of the cells, malignancy grades ranging from I to IV based on histological features, and molecular genetic markers. New approaches to brain tumor classification based on genomic methylation profiling (Capper et al. 2018) have also been recently developed which offer new insight and perspectives. Overview The incidence of primary CNS tumors is highly age-dependent. Medulloblastoma and pineal parenchymal tumors are mainly childhood tumors, whereas the most frequent primary brain tumors such as glioblastoma and meningioma are more frequent in adults, and their incidence strongly increases with age (Table 1). Between 2011 and 2015, the overall incidence rate of primary brain tumors was 23.03 per 100,000 in the US population, 5.65 per 100,000 between 0 and 14 years, 41.7 per 100,000 in adults aged of 40 years or more, and 83.75 per 100,000 in adults aged of 85 years or more (Ostrom et al. 2018). Glioblastomas are the most frequent primary malignant brain tumors. The median age at glioblastoma diagnosis is 65 years, and the annual incidence rate per 100,000 of glioblastoma is estimated at 15.13 in the 75-84 years population and 9.07 in the 85+ population (Ostrom et al. 2018). The median age at diagnosis of meningioma is 66 years. Meningioma represents the most frequent primary brain tumor and has an annual incidence rate of 40.8 in the 75-84 years population and 52.5 in the 85+ population (Ostrom et al. 2018). The incidence of CNS metastases should also increase in the future, due to aging of the