NSE, neuron-specific enolase, is a specific tumor marker for neuroendocrine tumors, and the normal reference range of NSE in clinical practice is 0-17.5 μg/L. Neuroenolase is mainly used for diagnosis, differential diagnosis and monitoring the therapeutic effect of small cell lung cancer after chemotherapy and radiotherapy treatment. In addition elevated NSE can also monitor recurrence and metastasis of small cell lung cancer, which occurs 4-12 weeks earlier than the confirmed diagnosis. It can also be used in neuroblastoma for disease change, efficacy evaluation, and to predict recurrence. Other neuroendocrine tumors such as pheochromocytoma, islet cell tumor, medullary thyroid carcinoma, and malignant melanoma can also be monitored using NSE, the upper limit of which is usually more than twice the standard value.