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.

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.