EGFR and head and neck squamous cell carcinoma: Although overexpression of EGFR is commonly observed in HNSCC, other cytogenetic and molecular alterations, including the expression levels of proteins and their activation, aberrant gene copy number (GCN), mutations, polymorphisms, and expression of EGFRvIII and ligands, also play important roles in HNSCC (Bossi et al., 2016).