EGFR and astrocytoma (excluding glioblastoma): According to the 2021 World Health Organization (WHO) classification, GBM is defined as an isocitrate dehydrogenase (IDH)-wild-type (IDH-wt), grade 4 astrocytoma, diagnosed by histological features (necrosis; microvascular proliferation) or molecular markers, including telomerase reverse transcriptase (TERT) promoter mutation, epidermal growth factor receptor (EGFR) amplification, or +7/−10 chromosomal alterations [5].