CEACAM5 and Pleural effusion: The CEA level in BALF of lung cancer patients with spicule sign, pleural effusion, and lesion diameter ≥ 3.0 cm was significantly higher than that without these symptoms, with statistically significant difference (P < 0.05), while ProGRP level in the BALF of lung cancer patients with lobulation sign, burr sign, ground glass sign, pleural effusion, and lesion diameter ≥ 3.0 cm was significantly higher than that of lung cancer patients without these symptoms, with statistically significant difference (P < 0.05) (Table 4).