242 - Long-Term Outcomes of Postoperative Radiotherapy for Patients with pIIIA-N2 Non-Small Cell Lung Cancer after Complete Resection and Adjuvant Chemotherapy: The Phase 3 PORT-C Randomized Clinical Trial

Y. Men¹, Y. Bao², N. BI², Z. Zhou², J. Liang², J. Lv², Q. Feng², Z. Xiao², Y. Wang³, J. Li³, J. Wang³, S. Gao⁴, L. H. Wang⁵, J. He⁴, and Z. Hui¹; ¹Department of VIP Medical Services & Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, ²Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, ³Department of Medical Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, Beijing, China, ⁴Department of Thoracic Surgery, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, ⁵Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, China, Shenzhen, China

Purpose/Objective(s): PORT-C trial was the first published phase III randomized clinical trial (RCT) to evaluate the role of postoperative radiotherapy (PORT) using IMRT/3DCRT in patients with resected pIIIA-N2 non-small cell lung cancer (NSCLC). Here we aimed to assess the long-term outcomes of this RCT. Materials/

Methods: Patients with pIIIA-N2 NSCLC treated with complete resection followed by 4 cycles of platinum-based chemotherapy between January 2009 and December 2017 were randomly assigned in a 1:1ratio with PORT or observation. The primary endpoint was disease-free survival (DFS) analyzed by modified intention-to-treat (mITT). Secondary end points included overall survival (OS), locoregional recurrence-free survival (LRFS), distant metastasis-free survival, and toxic effects. The rates of DFS, OS, LRFS, and DMFS were estimated using the Kaplan-Meier method, compared using the log-rank test, and modeled using the Cox proportional hazards method. Patterns of the first failures were analyzed using the competing risk analyses.
Results: A total of 394 patients were randomly allocated to PORT arm (n=184) or observation arm(n=180). The median follow-up time was 87.92 (95% CI, 81.84-94.00) months. In the mITT analyses, DFS was still no significant difference (HR,0.90; 95% CI, 0.70-1.12; p=0.39) between the PORT arm and the observation arm. The 5-year DFS rates were 36% in the PORT arm and 31.5% in the observation arm. The 5-year OS rates were 64.7% and 70.4% (p=0.20). In the per-protocol analyses, 140 patients were in the PORT arm and 170 patients in the observation arm, respectively. PORT was not significantly improved DFS (HR, 0.80; 95% CI, 0.61-1.05; p= 0.11) and OS (HR, 1.09; 95% CI, 0.77-1.53; p= 0.63). The majority of patients died of cancer. However, more cardiopulmonary disease caused deaths were observed in the PORT arm (3.3% vs 1.1%). The 5-year local recurrence only rates in the PORT arm was 10.4%, which was significantly lower than 18.9% in the observation arm.
Conclusion: The long-term results of PORT-C trial also indicated no DFS benefit by receiving PORT for pIIIA-N2 NSCLC patients after complete resection and adjuvant chemotherapy. The subset of patients fit PORT should be further identified.