Efficacy of thoracic radiotherapy in patients with stage IIIB–IV epidermal growth factor receptor-mutant lung adenocarcinomas who received and responded to tyrosine kinase inhibitor treatment

Purpose: Large-scale, prospective, randomized studies of the efficacy of thoracic radiotherapy (RT) in patients with unresectable stage IIIB–IV epidermal growth factor receptor (EGFR)-mutant lung adenocarcinomas who received and responded to EGFR tyrosine kinase inhibitor (TKI) treatment are not currently available. Therefore, we designed a propensity score-matched, nationwide, population-based, cohort study for estimating the effects of thoracic RT on patients with EGFR-mutant lung adenocarcinomas. Patients and methods: We analyzed patients with unresectable stage IIIB–IV EGFR mutant lung adenocarcinomas and categorized them into two groups according to treatment modality and compared their outcomes; groups 1 and 2 consisted of patients who received EGFR TKI treatment alone until tumor progression and those who received and responded to EGFR TKI treatment and subsequently received thoracic RT for lung tumors, respectively. The patients in groups 2 and 1 were matched at a ratio of 1:4. Results: The matching process yielded a final cohort of 1475 patients (1180 and 295 patients in groups 1 and 2, respectively) who were eligible for further analysis. According to both univariate and multivariate Cox regression analyses, the adjusted hazard ratios (aHRs) (95% confidence interval [CI]) derived for thoracic RT for lung tumor after EGFR TKI use and tumor response (group 2) compared with EGFR TKI treatment alone (group 1) was 0.72 (0.60–0.85). Conclusions: Thoracic RT might be associated with overall survival in patients with unresectable stage IIIB–IV EGFR-mutant lung adenocarcinomas who received and responded to EGFR TKI treatment.