Delirium is a common complication in elderly patients after surgery. And its occurrence is associated with worse outcomes. The causes of delirium are multifactorial but may include pain, stress response and inflammation. Dexamethasone is commonly used to prevent the occurrence of postoperative nausea and vomiting. In a randomized controlled trial, small-dose dexamethasone (8 mg) administered before anesthesia induction improved the quality of recovery in patients after cardiac surgery. Flurbiprofen axetil is commonly used to improve postoperative analgesia while decreasing the requirement of opioids. In a randomized trial of the investigators, combined use of flurbiprofen axetil with sufentanil for postoperative analgesia reduced delirium in elderly patients after orthopedic surgery. The purpose of this 2 plus 2 factorial randomized controlled trial is to test the hypothesis that combined use of dexamethasone and flurbiprofen axetil may reduce delirium in elderly patients after lung cancer surgery.