Are exon 19 deletions and L858R different in early stage lung adenocarcinoma?

Introduction: Evidence shows that exon 19 deletions (19del) and exon 21 Leu858Arg point mutation (L858R) of EGFR are different in response to EGFR tyrosine kinase inhibitor (EGFR-TKI) therapy in advanced lung cancers. However, the impact of the two mutational types in the early stage lung adenocarcinoma is unknown. Methods: We enrolled consecutive patients with operable adenocarcinoma which harbored 19del or L858R to investigate the clinicopathologic characteristics and prognostic outcomes. Results: Between 2008 and 2013, a total of 607 patients with 19del (47.9%) or L858R (52.1%) were included in this study. Clinicopathologic and disease-associated factors were well-balanced between 19del and L858R patients. Both recurrence-free survival (5-year RFS: 37.9% vs. 42.9%, p = 0.075) and overall survival (5-year OS: 64.7% vs. 60.7%, p = 0.741) were similar between the two groups. After relapse, 19del was associated with a better post-recurrence survival (PRS) than L858R ( p = 0.016). Multivariate analysis demonstrated that mutational types (HR = 1.521, 95% CI: 1.106-2.093, p = 0.01) and tyrosine kinase inhibitors (TKI) use after recurrence (HR = 0.422, 95% CI: 0.301-0.592, p < 0.001) were independent predictors of PRS. The 19del and L858R patients were similar regarding recurrent patterns, except on pleural/chest wall metastasis (26.0% vs. 12.2%, p = 0.007). Conclusions: Patients with the early stage lung adenocarcinoma harboring either 19del or L858R share similar RFS and OS. After recurrence, both could benefit from TKI therapy without the need for a second biopsy, but 19del seemed to be associated with better PRS. [ABSTRACT FROM AUTHOR]