Approximately 17% of patients with NSCLC have epidermal growth factor receptor-mutated (EGFRm) NSCLC,4 of whom 84% have what are referred to as common or classical EGFR mutations (ie, 46% exon 19 deletions [Ex19del] and 38% exon 21 codon p.Leu858Arg [L858R] substitutions) and 9% have less commonly occurring atypical or uncommon EGFR exon 20 insertions.5 The gene discussed is EGFR; the disease is non-small cell lung carcinoma.