Postoperative Radiotherapy (PORT) Improves Survivals of Resected pN2 Non-Small Cell Lung Cancer (NSCLC): A Propensity Score-Matched (PSM) Analysis

Abstract

To evaluate the effect of PORT on survivals as well as tumor control in patients with pN2 NSCLC after complete resection. From Jan. 2003 to Dec. 2015, patients with resected pN2 NSCLC at our institution were retrospectively studied. PSM analysis was conducted to generate comparable study arms. The effect of PORT on survivals (OS, DFS, LRFS, and DMFS) were evaluated using the Kaplan–Meier method and log-rank tests. Cox’s proportional hazards model was used for multivariate analysis. A statistically significant difference was set as p＜0.05. Totally 1434 patients were enrolled, including 341 (23.8%) in the PORT group and 1093 (76.2%) in the non-PORT group. The median follow-up time was 41.8 months. Patients treated with PORT had significantly longer OS (p＜0.001) and DFS (p=0.001) when compared with the control, as well as LRFS (p＜0.001) and DMFS (p=0.015). Multivariate analyses showed that PORT was an independent prognostic factor associating with better OS (HR=0.756, p=0.012). Moreover, we analyzed the effect of PORT on survivals for pⅢA–N2 NSCLC patients who received adjuvant chemotherapy using PSM to balance several covariates. After adjustment, PORT also significantly improved the survivals. The 3- and 5-year OS rates were 72.9% and 56.1%, respectively in the PORT group and were 62.6% and 41.7%, respectively in the control group (p=0.01). The 3- and 5-year DFS rates were 38.9% and 29.5%, respectively in the PORT group and were 21.6% and 13.2%, respectively in the control group (p＜0.001). The 3- and 5-year LRFS rates were 59.0% and 43.8% versus 38.3% and 20.5% in the PORT versus control group, respectively(p＜0.001). The 3- and 5-year DMFS rates were 44.5% and 33.2% versus 30.6% and 15.0% in the PORT versus control group, respectively (p＜0.0001). For NSCLC patients with resected pN2 or pⅢA-N2 receiving adjuvant chemotherapy, PORT can significantly improve the rates of OS, DFS, LRFS and DMFS. A prospective randomized multicenter clinical trial led by our institution is ongoing now.