Early tumor markers for lung cancer are rarely detectable. There are many markers for lung cancer, including proteins, endocrine substances, peptides and various antigenic substances such as CEA, soluble membrane antigens such as CA50, CA125, CA199. certain enzymes such as neurospecific enolase, NSE, CYFRA21-1, etc. Although they are helpful for the diagnosis of lung cancer, they lack specificity and have some reference value for the disease monitoring of certain lung cancers, i.e. their elevation is not only seen in lung cancer. For example, elevated CEA is also seen in gastrointestinal tumors, gynecological tumors, etc. Elevated NSE is also seen in neurogenic tumors, etc., which requires doctors to judge their clinical significance in conjunction with other clinical data of patients.