EGFR and non-small cell lung carcinoma: Among patients with EGFR-mutant NSCLC, differences in survival duration and responsiveness to EGFR TKI treatment have been observed depending on the type of EGFR somatic mutation (exon 21 point mutations versus exon 19 deletions) [22;23], suggesting that these two types of somatic mutations confer distinct biologic properties to NSCLC cells.