EGFR and cancer: There are two types of pathological alterations of EGFR in cancers: one is represented by a kinase-activating mutation in EGFR, which can lead to increased tyrosine kinase activity of EGFR and can be primary or secondary to anti-EGFR therapies [126,127], and the second is represented by the overexpression of the EGFR protein and may or may not be associated with gene amplifications [128,129,130,131].