Indications for postoperative radiotherapy for non-small cell lung cancer: 1. residual sarcoid tumor during surgery; 2. positive cut margins on pathological examination of surgical specimen cut margins; 3. no mediastinal lymph node dissection during surgery; 4. cut margins close to the tumor; 5. pathological examination of surgical specimen showing hilar lymph node metastasis N1 and/or mediastinal lymph node metastasis N2, especially in patients whose tumor has penetrated the lymph node envelope and entered the surrounding tissues; 6. high-risk patients with pathological and laboratory findings suggesting lymphatic and hematologic metastasis.