EGFR and non-small cell lung carcinoma: Although classical EGFR mutations are present in most cases of NSCLC responding to TKIs therapy, approximately 10–20% of patients who do show a clinical response to gefitinib do not have these EGFR mutations, indicating that other, than these classical mutations, may confer sensitivity to TKIs, or that EGFR mutations are not the sole determinants of TKI response (Sharma et al, 2007).