Impact of Radiotherapy Pattern on the Prognosis of Stage IV Lung Adenocarcinomas Harboring EGFR Mutations

Introduction The aim of this study was to investigate the role of local radiotherapy in the management of epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancers (NSCLCs) treated with EGFR tyrosine kinase inhibitors (TKIs). Materials and Methods Patients with stage IV EGFR-mutant NSCLC treated with radiotherapy concomitant to EGFR TKIs from May 2010 to December 2017 were retrospectively identified. Overall survival (OS) was the primary endpoints of the study. Results A total of 205 patients were enrolled in the study. One hundred eleven patients received one-time single-site radiotherapy (SSR), and 94 patients received multiple-site radiotherapy (MSR). Patients who received MSR had longer OS (median OS, 40.0 months; 95% confidence interval [CI], 29.6 to 50.4) than those who received SSR (median OS, 28.9 months; 95% CI, 24.3 to 33.5; P=0.031). Thoracic radiotherapy was associated with prolonged median OS (41.7 months, 95% CI, 29.0 to 54.4 vs 27.1 months, 95% CI 22.7 to 31.5; log-rank P<0.001). Multivariate analysis confirmed that thoracic radiotherapy was independently associated with improved OS (adjusted hazard ratio [HR], 0.514; 95% CI 32.3% to 81.8%; P=0.005). Conclusion MSR improves survival outcomes in patients with advanced-stage, EGFR-mutant, lung adenocarcinoma, with thoracic radiotherapy having the most significant effect on prognosis.