Non-small Cell Lung Cancer in South Wales: Are Exon 19 Deletions and L858R Different?

Background/Aim: In advanced non-small cell lung cancer (NSCLC), the epidermal growth factor receptor (EGFR) mutations L858R and exon 19 deletion (del19) predict response to EGFR tyrosine kinase inhibitors (TKIs). Trials have suggested a differential response to the second-generation EGFR TKI afatinib in favour of del19. We investigated whether this differential response is observed in clinical practice. Materials and Methods: Retrospective demographic, treatment and outcome data were collected on patients with: stage III/IV NSCLC and either del19 or L858R, receiving an EGFR TKI as first-line treatment. Results: There was no significant difference in overall survival (OS) between del19 (648 days, 95% confidence interval (CI)=461-835) and L858R (813 days, 95% CI=3871,238), (p=0.616), or in duration of therapy between del19 (365 days, 95% CI=192-538) and L858 (428 days, 95% CI=263-593), (p=0.928). Conclusion: Patients with exon del19 did not have a significantly longer OS with first-generation TKIs.