NSE is an abbreviation for neuron-specific enolase, which is an acidic protease specific to neurons and neuroendocrine cells and is a specific marker for neuroendocrine tumors. For example, in neuroblastoma, medullary thyroid carcinoma and small cell lung cancer, the NSE in normal human serum should be less than 12.5 units per milliliter. Currently, NSE is used as one of the important markers for small cell lung cancer in the clinic as an important indicator for diagnosis as well as judgment of healing and clinical follow-up, but it is not the only reference indicator and cannot be used as a basis for diagnosis. However, it is not the only reference index and cannot be used as a basis for diagnosis. Because an increased NSE does not mean 100% malignancy or clinical disease symptoms, it needs to be combined with imaging and other tests to make a comprehensive judgment. If NSE is higher than normal and there is no abnormality in chest X-ray and CT examination, it is recommended to follow up again in 3 months. If the NSE is still persistently elevated, a professional oncologist should be consulted to make a comprehensive judgment.