Postoperative radiotherapy and survival outcomes in pN2 non-small-cell lung cancer with positive surgical margins: An updated review of the National Cancer Database.

Abstract

e20010 Background: The role of postoperative radiotherapy (PORT) in non-small-cell lung cancer (NSCLC) remains controversial, particularly in patients with positive surgical margins (PSM). The 2022 Lung ART trial, a phase III study involving 501 European patients, found that mediastinal PORT did not improve disease-free survival (DFS) compared to no PORT; however, patients with PSMs were excluded from the trial. In 2020, Yuan et al. published a retrospective study in China on 113 pIIIA-N2 NSCLC patients with PSMs treated between 2003 and 2015, reporting no overall survival (OS) benefit with PORT. A subset analysis suggested a nonsignificant OS improvement in R1 resected patients receiving PORT with chemotherapy (52.4 months with PORT vs. 22.6 months without PORT, p=0.127). Since ASCO’s 2021 recommendation against routine PORT in completely resected pN2 NSCLC, no specific guidelines have addressed its use in patients with PSMs, highlighting the need for further research in this subgroup. Methods: The National Cancer Data Base (NCDB) was queried for M0 patients who underwent surgery for NSCLC with PSM (R1+R2), pathologic N2 status and those who received adjuvant chemotherapy from 2004-2017. Patients were stratified based on the administration of PORT, and cases with missing data were excluded. Survival outcomes were assessed using the SAS LIFETEST procedure. Multivariate analysis was not conducted as the NCDB does not capture performance status or re-resection data and residual confounding may influence results. Results: Of all the 7561 pN2 NSCLC patients identified, 818 had PSMs (R1+R2). After excluding patients with missing data, a total of 603 patients were included in the univariate analysis (PORT, n = 300; no PORT, n = 303). In this subgroup, the median OS was 27.53 months in the PORT group and 20.37 months in the non-PORT group (p=0.2175). Conclusions: In patients with PSMs and pN2 NSCLC who received adjuvant chemotherapy, PORT was associated with a numerical improvement in median OS; however, this difference was not statistically significant. The NCDB lacks critical data on re-resection, performance status, and key aspects of radiation quality, including dose, intent, and treatment volume, all of which may influence survival outcomes. These limitations underscore the need for prospective studies to better define the role of PORT, particularly in the R1 subgroup.