Postoperative Radiation Therapy (PORT) May Not Improve Overall Survival (OS) of Patients with pIIIA-N2 Non-Small-Cell Lung Cancer (NSCLC) with Positive Surgical Margins

Abstract

For pN+ NSCLC patients with positive surgical margins, the standard treatment is chemoradiotherapy. However, high level evidence is lacking. This study is to evaluate the effect of PORT on survivals of pIIIA-N2 NSCLC patients with positive surgical margins and identify the prognostic factors. Between Jan. 2003 and Dec. 2015, patients who had undergone lobectomy or pneumonectomy plus mediastinal lymph node dissection or systematic sampling in our single institution were respectively reviewed. Those with pIIIA–N2 NSCLC and positive surgical margins were included in this study. The Kaplan–Meier method was used to calculate survival rates, and the log-rank test was used to analyze differences between the groups. Multivariate analysis was done using the Cox hazard regression with entry factors of which the p-value <0.10. Statistically significant difference was set as p-value <0.05. Of all the 1547 pIIIA–N2 NSCLC patients, 113 were with positive surgical margins, including 76 with R1-resection and 37 with R2-resection. Of the 113 patients, 32 (28.3%) received radiotherapy. There was no significant difference in OS between patients with R1-resection and with R2-resection. The 5-year OS rates were 35.1% and 19.2% respectively (p=0.373). OS was more favorable for patients with less positive lymph nodes (p=0.039). In PORT group, the 3- and 5-year OS rates were 33.9% and 22.6% respectively, which were similar with 40.1% and 35.3% in non-PORT group (p=0.970). Subset analysis showed that for patients with R1-resection and non-squamous cell carcinoma (n=44), PORT trended to improve OS, with the 5-year OS rates of 35.7% versus 23.8% (p=0.082). In multivariate analysis with entry factors including age, the number of positive lymph nodes and different adjuvant therapies, there was no significant independent factor in predicting OS. For pIIIA-N2 NSCLC patients with positive surgical margins in our study, PORT does not improve OS, but trends to improve the OS of those with R1-resection and non-squamous cell carcinoma. Further study with a larger population is needed to validate our conclusion.