To Evaluate the Role of Postoperative Radiotherapy in Patients With IIIA(N2) Non-Small Cell Lung Cancer

OBJECTIVES: 1. Primary * Investigate the value of PORT for completely resected pathologic stage IIIa(N2) NSCLC by comparing the disease-free survival of patients with low risk of LRR treated with PORT vs no PORT. 2. Secondary * Determine the overall survival of patients treated with these regimens. * Compare the locoregional recurrence-free survival in patients treated with these regimens. * Compare the distant metastasis-free survival in patients treated with these regimens. * Determine patterns of recurrence in patients treated with these regimens. * Determine the treatment-related adverse events of these regimens in these patients. * Determine the prediction models for locoregional recurrence and brain metastasis based on the clinical, pathological, radiological, genetic, tumor microenvironmental and immunological data. OUTLINE: This is a multicenter, randomized study. The clinical risk prediction model for LRR has been established based on our large institutional database. On multivariate analysis, heavy cigarette smoking history, cN2 status, and number of involved lymph nodes\>4 were independently significant factors predicting high risk of LRR. The PI equation was built including the three categorical variables and coefficients based on their level of significance: PI＝(0.9×smoking history)＋(0.5×clinical N status)＋(0.8×number of involved lymph nodes). Patients with the PI score\<3.5 were considered as low risk of LRR. Patients are stratified according to participating center, EGFR mutation status (EGFR 19del or 21L858R mutations vs others), and use of pretreatment positron emission tomography scans (yes vs no). Patients are randomized to 1 of 2 treatment arms. Arm I (PORT): Participants in the Arm I will receive four cycles of adjuvant chemotherapy and after that, sequential adjuvant thoracic conformal radiotherapy (50.4 Gy, 1.8 Gy once daily over 5.5 weeks) will be administered. PORT begins within 2-6 weeks after chemotherapy. Arm II (no PORT): Participants in the Arm II will receive four cycles of adjuvant chemotherapy and do not undergo adjuvant thoracic conformal radiotherapy. PROJECTED ACCRUAL: A total of 300 patients will be accrued for this study.