Prognostic Value of Exon 19 Versus 21 EGFR Mutations Varies According to Disease Stage in Surgically Resected Non-small Cell Lung Cancer Adenocarcinoma.

Background: The prognostic value of exon 19 and 21 EGFR mutations in stage IV non-small cell lung cancer (NSCLC) is well established.

Objective: We aimed to evaluate the prognostic value of the mutations in surgically resected NSCLC.

Methods: We retrospectively reviewed data from 1798 surgically resected NSCLC adenocarcinomas between 2007 and 2017 in three departments of thoracic surgery (Nancy/Strasbourg, France, and Torino, Italy) for whom mutational status was known. Overall survival (OS) was evaluated using log-rank and Cox proportional hazard models.

Results: EGFR exon 19 deletion was observed in 108 patients (55.1%) and exon 21 L858R mutations were observed in 88 patients (44.9%). In stage I, the median OS was not significantly different between exons 19 and 21 (p = 0.54), while, in stage II, the median OS reached 65 months [95% confidence interval (CI) 41.67-88.33] for exon 19 mutations and decreased to 48 months for exon 21 mutations (95% CI 44.21-51.79; p = 0.027). In multivariate analysis, exon 19 deletion remained a favorable prognostic factor [hazard ratio (HR) 0.314, 95% CI 0.098-0.997; p = 0.05]. In stage III, the median OS reached 66 months (95% CI 44.67-87.32) for exon 19 mutations and decreased to 32 months for exon 21 mutations (95% CI 29.86-34.14; p = 0.03). In multivariate analysis, exon 19 deletion remained a significantly favorable prognostic factor (HR 0.165, 95% CI 0.027-0.999; p = 0.05).

Conclusion: The prognostic value of EGFR exon 19 and 21 mutations appears to be different according to disease stage in surgically resected NSCLC.