To examine the serum levels of carcinoembryonic antigen (CEA), cytokeratin-19 fragments (CYFRA21-1), neuron-specific enolase (NSE), carbohydrate antigen (CA) 19-9, CA125, tissue polypeptide antigen (TPA), tissue polypeptide specific antigen (TPS), and lactate dehydrogenase (LDH) to predict de novo metastatic lung adenocarcinoma.