Utility of CEA and CA 15-3 Measurements in Non-Purulent Pleural Exudates in the Diagnosis of Malignancy: A Single-Center Experience

Abstract Objective To establish the diagnostic accuracy of pleural fluid (PF) CEA and CA 15-3 in identifying malignancy, and to determine the additional value of these markers in patients with malignant pleural effusions (MPEs) with false negative results from cytological fluid examination. Methods PF concentrations of CEA and/or CA 15-3 were determined in 1575 patients with non-purulent exudates, 549 of whom had confirmed MPEs, 284 probable MPEs, and 742 benign effusions. Tumor marker cut-off points were set to ensure 100% specificity for malignant effusion. Results The 41%, 40% and 60% of MPE patients had high PF levels of CEA (>45 ng/mL), CA 15-3 (>77 UI/l) or both, respectively. These percentages were 30%, 19% and 41% in MPEs with positive pleural biopsy and negative PF cytology; and 24%, 13% and 35% in clinical MPEs without histocytological confirmation. Tumor markers were of no value in lymphomas and mesotheliomas. The area-under-the-curve for CEA was 0.819 (95% CI: 0.793–0.845) and for CA 15-3, it was 0.822 (95% CI: 0.796–0.847). The use of tumor markers compared to cytology alone, increased the diagnosis of malignancy by 14%. Conclusions Measurements of PF CEA and CA 15-3 may complement pleural cytology in the identification of MPEs.