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

Abstract

The prognostic value of exon 19 and 21 EGFR mutations in stage IV non-small cell lung cancer (NSCLC) is well established. We aimed to evaluate the prognostic value of the mutations in surgically resected NSCLC. 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. 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). The prognostic value of EGFR exon 19 and 21 mutations appears to be different according to disease stage in surgically resected NSCLC.