Three markers of lung tumor are three markers (various types of antigens or special proteins secreted) selected from lung tumors to be tested to screen for lung malignancy or to assess the treatment effect and prognosis of malignant tumors. 1. Common lung tumor markers (1) Small cell lung cancer: neuron-specific enolase (NSE), gastrin-releasing peptide precursor (ProGRP). (2) Lung squamous carcinoma: cytokeratin 19 fragment (CYFRA21-1), squamous cell carcinoma-associated antigen (scc). (3) Lung adenocarcinoma: carcinoembryonic antigen (CEA). (4) Non-specific antigens: tissue polypeptide antigen (TPA), glycan antigens CA125, CA153, serum C-reactive protein (CRP), KT1. 2. Common combinations of three lung tumor markers: ① CRFRA21-1, CEA and KT1 ② CRP, SCC, CEA ③ CEA, SCC, NSE ④ CEA, CYFRA211, TPA. Different patients have different purposes of examination, and different combinations of the three markers for lung tumors are selected, so it is recommended to consult the doctor further in the hospital.