BACKGROUNDTo evaluate the values of a new tumor marker carbohydrate antigen (CA242) and combined determination of CA242, tissue polypeptide antigen (TPA), neuron-specific enolase (NSE) and carcinoembryonic antigen (CEA) in the diagnosis of malignant pleural effusion associated with lung cancer.

METHODSThe concentration of CA242, TPA, NSE and CEA in the serum and the pleural effusion was measured in 57 patients with malignant pleural effusion associated with primary lung cancer and 30 patients with tuberculous pleural effusion by enzyme-linked immunosorbent assay.

RESULTSThe levels of the four tumor markers in the serum and pleural effusion from patients with lung cancer were significantly higher than those with tuberculous pleural effusion (P < 0.01). The sensitivity of CA242 in the serum and the pleural effusion for lung cancer was 53.6% (31/57) and 61.4% (35/57) respectively; the sensitivity of CA242 for lung adenocarcinoma was 65.7% (23/36) and 66.7% (24/36) respectively. The specificity was 90.0%. Combined determination of the four tumor markers in serum and pleural effusion: If two or more of them were positive for evidence for diagnosis of lung cancer, the specificity for the serum and the pleural effusion was 96.7% (29/30) and 100.0% (30/30) respectively, with the sensitivity of 75.4% (43/57) and 77.2% (44/57) respectively.

CONCLUSIONSThe determination of the new tumor marker CA242 in serum and pleural effusion might be useful for the diagnosis of malignant pleural effusion associated with lung cancer, especially for adenocarcinoma. The combined determination of the four tumor markers can increase the specificity and the sensitivity in the diagnosis of malignant pleural effusion.