The aim of this study was to evaluate the efficacy of postoperative radiotherapy (PORT) in stage pIIIA-N2 non-small cell lung cancer (NSCLC) patients with positive surgical margins.

Between January 2003 and December 2015, patients who had undergone lobectomy or pneumonectomy plus mediastinal lymph node dissection or systematic sampling in our single institution were retrospectively reviewed. Those with pIIIA-N2 NSCLC and positive surgical margins were enrolled into the study. The Kaplan-Meier method was used for survival analysis, and the log-rank test was used to analyze differences between the groups. Univariate and multivariate analyses using Cox proportional hazards regression models were performed to evaluate potential prognostic factors for OS. Statistically significant difference was set as P < 0.05.

Of all the 1547 patients with pIIIA-N2 NSCLC reviewed, 113 patients had positive surgical margins, including 76 patients with R1 resection and 37 with R2 resection. The median overall survival (OS) was 28.3 months in the PORT group and 22.6 months in the non-PORT group (P = 0.568). Subset analysis showed that for patients with R1 resection, the median OS was 52.4 months in the PORT group which was nonsignificantly longer than that of 22.6 months in the non-PORT group (P = 0.127), whereas PORT combined with chemotherapy could significantly improve OS, with a median OS of 52.4 months versus 17.2 months (P = 0.027). For patients with R2 resection, PORT made no significant difference in OS (17.6 vs. 63.8 months, P = 0.529).

For pIIIA-N2 NSCLC patients with positive surgical margins, PORT did not improve OS, but OS was improved in those patients who underwent R1 resection combined with chemotherapy.

SIGNIFICANT FINDINGS OF THE STUDY: Significant findings of the study: Postoperative radiotherapy (PORT) has been recommended to treat patients with positive surgical margins. However, the existing evidence is controversial and high-level evidence is lacking.

What this study adds: The PORT group had markedly, but not statistically significant, longer median OS compared with the non-PORT group in patients with R1 resection. OS was significantly longer in the patients with R1 resection receiving adjuvant CRT than the surgery alone group.