AFP and lung carcinoma: The clinical value of carcinoembryonic antigen (CEA), carbohydrate antigen 125 (CA-125), carbohydrate antigen 199 (CA-199), alpha-fetoprotein (AFP), neuron-specific enolase (NSE), cytokeratin 19 fragment (CYFRA21-1), and carbohydrate antigen 15 − 3 (CA15-3) in lung cancer has been widely concerned [18].