Mild elevation of NSE after early stage lung cancer surgery may be a sign of recurrence, but it is not certain, and needs to be combined with imaging examination to be sure. NSE is neuron-specific enolase, which is an important diagnostic marker for small-cell lung cancer. When the condition of lung cancer patients is under control after surgery, the level of NSE can be restored to the normal range, and if the elevation occurs in the later stage, it may be a recurrence of lung cancer, or it may be caused by pneumonia, traumatic brain injury, cerebral infarction, etc. It is not 100% certain that it is the recurrence of lung cancer, and it is necessary to improve the imaging examination of head, chest, abdomen, whole body bones, etc. in a timely manner. It is also necessary to improve the imaging examination of head, chest, abdomen and bones of the whole body in time. If the NSE keeps increasing and tumors are found in the surgery site or other places, it means that the patient has recurrence and needs to take chemotherapy and local radiotherapy.