EGFR and neoplasm: Tumor variants can be classified on the basis of somatic mutations in isocitrate dehydrogenase (IDH) 1/2 and TP53; transcriptional signature (classical, mesenchymal, neural, or proneural); copy number variation, including co-deletion of chromosomes 1p and 19q; and amplification or mutation of the epidermal growth factor receptor (EGFR) and increased DNA hypermethylation of promoter-associated CpG islands (Figure 1) (5–10).