Xiao Chen has been coughing and occasionally sputum recently, although he is less than 40 years old, but the serious haze and a pack of cigarettes a day also made him worry that his lungs have grown something, to the hospital, the doctor prescribed a chest X-ray, a blood test for a lung tumor marker, chest X-ray except for increased lung texture is not a big problem, lung tumor marker CEA (carcinoembryonic antigen) showed 8,2, which was several points higher than the normal value (0-5), which scared Xiao Chen. So, what indicators are included in the lung tumor markers? Does an elevated level mean a tumor in the lung? First of all, lung tumor markers include four indicators, CEA (carcinoembryonic antigen), NSE (neuronal enolase), CYFRA21-1 (cytokeratin 19 fragment), SCC (squamous cell carcinoma antigen) CEA (carcinoembryonic antigen) CEA is a fetal protein present in adult cancer tissues, a variety of solid tumors can cause CEA elevation, among lung cancer, CEA of lung adenocarcinoma is more obviously elevated. CEA is a useful indicator in the diagnosis, prognosis, and prediction of recurrence of cancer. 98% of non-smokers have CEA < 5ug/L. About 39% of smokers have higher than normal CEA. NSE (neuronal enolase) In lung cancer, NSE is a sensitive adjuvant diagnostic indicator for small cell lung cancer and can be used to aid in the diagnosis and monitor the effectiveness of treatment of small cell lung cancer. NSE concentration gradually decreases to normal levels when treatment is effective and increases upon recurrence. Using NSE elevation to monitor recurrence is 4-12 weeks earlier than clinical determination of recurrence. CYFRA21-1 (cytokeratin 19 fragment), which consists mainly of two monoclonal antibodies to cytokeratin 19, is present in the cytoplasm of monolayer and complex epithelial tumor cells, and the lysed fragment is released into the serum when the cells die, resulting in elevated serum levels of CYFRA21-1. Among lung cancers, lung squamous carcinomas have higher CYFRA21-1 levels than adenocarcinomas and small cell carcinomas. SCC (squamous cell carcinoma antigen) SCC is a marker of squamous epithelial carcinoma, and SCC is elevated in all kinds of squamous carcinomas. The positive rate of squamous lung cancer is 46-90%, and the concentration of SCC in serum follows the disease. As mentioned earlier, CEA is higher than normal in about 39% of smokers, and several other indicators are similar. Therefore, similar to Xiao Chen's case, it does not mean that the elevation of one of the lung tumor markers means that there is a tumor growing on the lung, it needs to be combined with imaging examination to determine. Of course, if the tumor markers continue to rise in multiple blood tests, tumor lesions should be highly suspected.