The serum tumor markers associated with lung cancer include NSE, SCC, CEA, CA125, Cyfra21-1, etc. However, the sensitivity and specificity of these indicators are not high, so their value in lung cancer diagnosis is limited, and some lung cancer patients do not have high tumor markers. At present, tumor markers are mainly used for research in monitoring treatment response, early monitoring of recurrence, and suggesting prognosis. Carcinoembryonic antigen CEA: CEA is a fetal protein present in adult cancer tissues, and CEA was discovered in 1965. It is an acidic glycoprotein. It was initially thought to be a marker for colon cancer (elevated in 60% to 90% of patients), but was later found to be highly expressed in pancreatic (80%), gastric (60%), lung (75%) and breast (60%) cancers as well. CEA measurement is a useful indicator for the diagnosis of cancer, prognosis, and recurrence prediction. Neuron-specific enolase (NSE): 1. It can be used as an aid in the diagnosis and monitoring of the therapeutic effect of small cell lung cancer. The NSE concentration gradually decreases to normal level when the treatment is effective, and increases when the recurrence occurs. 2.It can be used to monitor the change of neuroblastoma, evaluate the efficacy and forecast the relapse. 3.Serum NSE may also be increased in endocrine tumors, such as pheochromocytoma, islet cell tumor, medullary thyroid carcinoma, melanoma, and retinoblastoma. Squamous cell carcinoma antigen (SCC): SCC is a marker of squamous epithelial carcinoma, and SCC is elevated in all kinds of squamous carcinomas. The positive rate of lung squamous carcinoma is 46-90%, and the concentration of SCC in serum increases with the aggravation of the disease. Glycoantigen 125 (CA125): malignant tumors such as lung cancer, ovarian cancer, endometrial cancer, fallopian tube cancer, pancreatic cancer, gastric cancer, breast cancer, esophageal cancer, etc. can also be elevated.