Long-term outcomes of postoperative radiotherapy for patients with pIIIA-N2 non-small-cell lung cancer after complete resection and adjuvant chemotherapy (PORT-C): a single-centre, randomized, phase 3 trial.

Background: The PORT-C trial was the first published phase III randomized clinical trial (RCT) to evaluate the role of postoperative radiotherapy (PORT) using intensity-modulated radiation therapy (IMRT)/three-dimensional conformal radiation therapy (3D-CRT) in patients with resected pIIIA-N2 non-small-cell lung cancer (NSCLC). We aimed to assess the long-term outcomes of this RCT. Methods: Patients with pIIIA-N2 NSCLC treated with complete resection followed by four cycles of platinum-based chemotherapy between January 1, 2009 and December 31, 2017 were randomly assigned in a 1:1 ratio to PORT or observation. Radiotherapy was delivered using a 6 MV-X ray linear accelerator via 3D-CRT or IMRT, with 2 Gy per fraction up to 50 Gy over 5 weeks. The primary endpoint was disease-free survival (DFS), analyzed using modified intent-to-treat (mITT). Secondary endpoints included overall survival (OS), locoregional recurrence-free survival (LRFS), distant metastasis-free survival (DMFS), and toxic effects. DFS, OS, LRFS, and DMFS rates were estimated using Kaplan-Meier method, compared using log-rank test, and modeled using Cox proportional hazards method. The patterns of first failures were analyzed using competing risk analyses. This trial is registered with ClinicalTrials.gov, NCT00880971. Findings: Overall, 394 patients were randomly allocated to the PORT (n = 184) or observation (n = 180) arms. The median follow-up time was 87.9 months (interquartile range [IQR] 72.2-113.8). In the mITT analyses, DFS showed no significant difference between the PORT and observation arms (hazards ratio [HR], 0.90; 95% CI, 0.70-1.12; p = 0.39). The 5-year DFS rates in the PORT and observation arms were 36% (95% confidence interval [CI], 28.9%-43.1%) and 31.5% (95% CI, 24.6%-38.4%), respectively; the 5-year OS rates were 64.7% (95% CI, 57.6%-71.8%) and 70.4% (95% CI, 63.5%-77.3%), respectively (p = 0.20). In the per-protocol analyses, 140 and 170 patients were included in the PORT and observation arms, respectively. PORT did not significantly improve DFS (HR, 0.80; 95% CI, 0.61-1.05; p = 0.11) or OS (HR, 1.09; 95% CI, 0.77-1.53; p = 0.63). Most patients died of cancer. However, more deaths due to cardiopulmonary disease were observed in the PORT arm than in the observation arm (6/184, 3.3% vs. 2/180, 1.1%). The first failure of locoregional recurrence (LR)-only was significantly lower in the PORT arm than in the observation arm (10.9%, 95% CI, 6.8%-15.9% vs. 18.9%, 95% CI, 14.0%-26.2%, p = 0.031). Only 1 patient (0.5%) in the PORT arm had grade 3 radiation pneumonitis. No radiotherapy-related grade 4 or 5 AEs were observed. Interpretation: The long-term results of the PORT-C trial indicated no DFS benefit from receiving PORT for patients with pIIIA-N2 NSCLC after complete resection and adjuvant chemotherapy. Funding: National Key R&D Program of China, National Natural Science Foundation of China, Capital's Funds for Health Improvement and Research, Beijing Hope Run Special Fund of Cancer Foundation of China, and Beijing Xisike Clinical Oncology Research Foundation.