Mediastinal radiotherapy after adjuvant chemotherapy for resected non–small cell lung cancer with N2 lymphadenopathy: A novel meta-analysis

INTRODUCTION: Treatment for stage IIIA N2 non–small cell lung cancer (NSCLC) typically involves a combination of chemotherapy, radiotherapy, and surgery, but the optimal sequencing is not determined. Local recurrence rates following surgery remain high, and the role of postoperative radiotherapy (PORT) in N2 disease is unclear. This meta-analysis aims to determine whether PORT provides additional survival advantage beyond observation for patients with stage IIIA N2 disease who have undergone complete surgical resection and received adjuvant chemotherapy. METHODS: All studies comparing adjuvant chemotherapy and PORT versus adjuvant chemotherapy alone after curative surgical resection for stage IIIA N2 NSCLC were included. Meta-analysis was performed using random effects modelling in accordance with MOOSE (Meta-Analyses and Systematic Reviews of Observational Studies) guidelines. Subgroup analysis, heterogeneity, and risk of bias were assessed, with meta-regression to determine the effects of patient and tumor characteristics on outcomes. RESULTS: Ten studies with a pooled dataset of 18,077 patients (5453 PORT, 12,624 no PORT) were included. PORT significantly improved both overall survival (OS) and disease-free survival (DFS) at 1 year (OS: hazard ratio [HR], 0.768; DFS: HR, 0.733), 3 years (OS: HR, 0.914; DFS: HR, 0.732), and 5 years (OS: HR, 0.898; DFS: HR, 0.735, all P < .0001). These effects were independent of specific patient or tumor characteristics. CONCLUSIONS: This study demonstrates a significant DFS and OS benefit from the addition of PORT following adjuvant chemotherapy. We advocate the consideration of PORT for such patients following specialist multidisciplinary assessment and comprehensive discussion of the benefits and risks of treatment.