952P Effect of thoracic radiotherapy timing on prognosis for patients with late-staged lung adenocarcinoma harboring EGFR mutations

Abstract

Studies confirmed that thoracic radiotherapy combined with EGFR-TKIs (EGFR-tyrosine kinase inhibitors, EGFR-TKIs) can improve the prognosis of advanced lung adenocarcinoma patients with EGFR sensitive mutations. However, the optimal timing of radiotherapy intervention still needs to be clarified. This study aimed to investigate the effect of thoracic radiotherapy intervention on the prognosis of patients at different time points in the process of targeted therapy by analyzing the related clinical cases to provide evidence for determining the optimal therapy regimen of thoracic radiotherapy combined with EGFR TKIs. Patients with EGFR mutant lung adenocarcinoma who received thoracic radiotherapy were included in present study. According to the timing of thoracic radiotherapy in the process of targeted therapy, the patients were divided into two groups: radiotherapy before drug resistance and radiotherapy after drug resistance. Medical data were analyzed for overall survival (OS) and thoracic progression-free survival (TPFS). Survival curve for the two groups were determined using the Kaplan-Meier method. the hazard ratios were reported as relative risks with their corresponding 95% confidence intervals (CIs). P <0.05 was considered statistically significant. A total of 129 patients met the inclusion criteria in this retrospective study, 66 and 63 patients respectively included in the groups of thoracic radiotherapy before drug resistance and after drug resistance. The median TPFS and OS of the entire cohort were 16.1 months and 42.1 months. The median OS of patients in thoracic radiotherapy before and after drug resistance groups were 52 and 34.5 months respectively (hazard ratio: 1.507, 95% confidence interval: 1.004–2.264, P<0.05). The median TPFS of patients with radiotherapy before EGFR-TKIs resistance was significantly longer than that of patients in another group (33.1 months vs 10.4 months, hazard ratio: 3.183, 95% confidence interval: 2.119–4.780, P<0.0001). The early application of thoracic radiotherapy, at least until EGFR-TKIs resistance, for the primary lesion may improve the survival of patients with advanced EGFR mutant lung adenocarcinoma.