CEACAM5 and Pleural effusion: For improved efficacy in the clinical diagnosis of malignant pleural effusion associated with lung cancer, in this study, the levels of CEA, CA125 and SP70 antigens were measured in pleural effusion specimens and serum specimens from NSCLC patients combined with malignant pleural effusion in our hospital, and compared with those of NSCLC patients with pleural effusion.