The 2021 WHO classification further expanded the relevance of molecular diagnostics, adding isocitrate dehydrogenase (IDH) mutational status and 1p/19q co-deletion to better define glioma subtypes; currently, a diffuse astrocytic glioma with microvascular proliferation, necrosis, and/or specific gene alterations (i.e., TERT mutation, epidermal growth factor receptor (EGFR) amplification, and chromosome rearrangement, IDHwt without 1p/19q co-deletion) is diagnosed as GBM WHO grade 4 [9]. Here, EGFR is linked to central nervous system cancer.