Pleural fluid carcinoembryonic antigen as a biomarker for the discrimination of tumor-related pleural effusion

ObjectivesTo assess the value of tumor biomarkers in the determination of tumor-related pleural effusion (PE). Cytological examination of the pleural fluid has a limited sensitivity in diagnosing tumor PE. MethodsPleural fluid and serum samples were obtained from 1137 patients and PE etiology was determined by multiple diagnostic techniques. Carcinoembryonic antigen (CEA) levels were measured in both pleural fluid and serum samples. Levels of cancer antigen (CA) 125, glucose, and lactate dehydrogenase (LDH) were assessed in pleural fluid specimens. Results601 PE patients were diagnosed with tumors, while 595 tested individuals were tumor-free. Among the measured biomarkers, pleural fluid CA 125, glucose, and LDH levels, and serum CEA amounts were comparable between tumor and tumor-free PE patients (P>0.05). Only pleural fluid CEA levels were significantly different between the two groups (P<0.05). A CEA cutoff of 2.645 ng/mL yielded sensitivity and specificity of 69.4% and 82.2%, respectively, for tumor-related PE detection. The area under the curve for CEA was 0.740 (95%CI: 0.710-0.770). ConclusionCEA levels in pleural fluid were a potential biomarker for the detection of tumor-related PE. These findings provide an easy and simple method for clinical screening and detection of PE.