EGFR and non-small cell lung carcinoma: The two most common mutations, in-frame deletions in exon 19 (Ex19del) affecting the amino acid motif LREA (E746–750del) and substitution of arginine for leucine at position 858 (L858R) in exon 21, are referred to as “classical” EGFR mutations and together account for approximately 85% of EGFR mutations in patients with NSCLC [40].