In this study, the relationship between CT features and the concentrations of CEA and ProGRP in BALF was analyzed to find that the levels of CEA and ProGRP in BALF of lung cancer patients with burr sign, pleural effusion, and lesion diameter ≥ 3.0 cm were significantly increased, showing that there was a certain relationship between CT features and CEA and ProGRP levels in patients with lung cancer. The gene discussed is CEACAM5; the disease is Pleural effusion.