Overall survival (OS) is significantly shorter for astrocytomas harboring CDKN2A/B deletions in both pediatric and adult patients (21, 71), and therefore the CNS5 classification now upgrades astrocytomas with CDKN2A/B homozygous deletion to WHO grade 4 irrespective of high grade histology features with microvascular proliferation or necrosis (58). Here, CDKN2A is linked to astrocytoma (excluding glioblastoma).