The 2021 WHO CNS5 classification of brain tumors has updated the diagnosis and definition of GBM by integrating molecular features such as IDH wild type, EGFR amplification, TERT promoter mutation, and CDKN2A/2B deletion, highlighting the predominant role of endogenous biological events in GBM diagnosis [2]. This evidence concerns the gene CDKN2A and glioblastoma.