Role of Postoperative Radiotherapy on High-Risk Stage pIIIA-N2 Non-Small Cell Lung Cancer Patients After Complete Resection and Adjuvant Chemotherapy: A Retrospective Cohort Study

Abstract

Background The aim of the study was to assess the effectiveness of postoperative radiotherapy in high-risk patients with stage pIIIA-N2 non-small cell lung cancer (NSCLC) following complete resection and adjuvant chemotherapy. Methods Data from NSCLC patients within the Surveillance, Epidemiology, and End Results (SEER) database were analyzed. The study examined the association between lymph node ratio (LNR) and both cancer-specific survival (CSS) and overall survival (OS) using restricted cubic spline curves. Patients were categorized into high- and low-risk groups based on established LNR cut-off values, and survival outcomes were compared between those receiving postoperative radiotherapy and those who did not within the high-risk group. Results The study included 1,690 patients. An LNR threshold of 0.29 was identified for both CSS and OS. Patients with an LNR ≥ 0.29 demonstrated significantly worse CSS (hazard ratio (HR) = 1.56, 95% confidence interval (CI): 1.37 - 1.78; P < 0.001) and OS (HR = 1.44, 95% CI: 1.28 - 1.62; P < 0.001) compared to those with an LNR < 0.29. In the high-risk group (LNR ≥ 0.29), postoperative radiotherapy did not significantly affect CSS (HR = 0.98, 95% CI: 0.82 - 1.17; P = 0.809) or OS (HR = 0.95, 95% CI: 0.81 - 1.11; P = 0.533). Conclusions LNR is a significant prognostic factor in patients with stage pIIIA-N2 NSCLC post complete resection and adjuvant chemotherapy. A higher LNR (≥ 0.29) is associated with poorer CSS and OS. However, postoperative radiotherapy does not confer survival benefits in these high-risk patients. Our findings suggest that postoperative radiotherapy should not be routinely performed in this subgroup. Further research is required to explore effective treatment strategies for these patients.