BACKGROUNDMalignant pleural effusion is usually caused by lung cancer, and tumor markers may be helpful to its differential diagnosis. The aim of this study is to explore the clinical value of serum and pleural effusion pro-gastrin-releasing peptide (ProGRP), neuron specific enolase (NSE), cyto- keratin fragment 19 (CYFRA21-1) and carcinoembryonic antigen (CEA) in differential diagnosis and histological typing of malignant pleural effusion caused by lung cancer.

METHODSAccording to histological type of primary tumor, 99 patients with malignant pleural effusion caused by lung cancer were divided into small cell lung cancer (SCLC) group, adenocarcinoma group and squamous cell carcinoma group, with 37 patients with benign pleural effusion and 35 healthy persons as controls. Diagnostic value of serum and pleural effusion ProGRP , NSE, CYFRA21-1 and CEA was evaluated for each group.

RESULTSThe levels of ProGRP, NSE, CYFRA21-1 and CEA in serum and pleural effusion of all the malignant groups were significantly higher than those in the control groups (P < 0.01). In the SCLC group, detection of pleural effusion ProGRP showed the highest Youden index and accuracy. In the adenocarcinoma group and squamous cell carcinoma group, combined detection of pleural effusion CEA+CYFRA21-1 (on parallel test) showed the highest Youden index and accuracy.

CONCLUSIONSDetection of pleural effusion tumor markers ProGRP, CYFRA21-1, NSE and CEA is of great clinical value in differential diagnosis and histological typing of malignant pleural effusion. Pleural effusion ProGRP is the optimal tumor marker for malignant pleural effusion caused by SCLC. Pleural effusion CEA+CYFRA21-1 (on parallel test) is a good auxiliary diagnosis index for malignant pleural effusion caused by adenocarcinoma and squamous cell carcinoma of the lung.