Effect of preoperative radiotherapy on overall survival in N2 non-small-cell lung cancer: a propensity score-matched analysis of Surveillance, Epidemiology, and End Results database

OBJECTIVES: The aim of this study was to investigate the effect of preoperative radiotherapy (PrORT) on the overall survival (OS) of patients with stage ipsilateral mediastinal lymph node metastasis (N2) non-small-cell lung cancer. METHODS: A total of 1390 patients with stage N2 non-small-cell lung cancer between 2010 and 2015 were identified from the Surveillance, Epidemiology, and End Results database. The efficacy of PrORT combined with surgery was compared with that of surgery alone on OS. Propensity score matching (PSM) was performed to balance the baseline characteristics of patients who received (n = 239) and did not receive (n = 1151) PrORT. We compared the OS of the 2 groups using the Kaplan-Meier method and log-rank were used to compare the OS between the 2 groups test before and after PSM and to analyse subgroups of patients with squamous cell carcinoma (SCC) and adenocarcinoma. RESULTS: In whole group analysis before PSM, the median OS was superior in the PrORT group than in the surgery alone group (44.0 [34.4-56.6] vs 39.0 [34.5-43.5] months). There was a significant difference in OS [hazard ratio (HR): 0.819; 95% confidence interval (CI): 0.677-0.991; P = 0.029]. Nevertheless, no statistically significant difference was found in OS between the 2 groups after PSM (HR: 0.856; 95% CI: 0.654-1.122; P = 0.260). Among subgroup analysis of the SCC group before PSM revealed that patients who received PrORT had significantly higher median OS than those who did not receive PrORT (52.0 [40.0-NA] vs 27.0 [22.0-32.0] months; HR: 0.591, 95% CI: 0.442-0.792, P = 0.000) and the differences in OS existed after PSM (P = 0.043). However, no significant difference was found in OS before and after matching in the adenocarcinoma group (P = 0.827 and P= 0.801, respectively). CONCLUSIONS: PrORT demonstrated an OS benefit for patients with stage N2 lung SCC; however, further prospective randomized clinical trials are warranted to confirm this finding.