Utility of CEA and CA 15-3 measurements in non-purulent pleural exudates in the diagnosis of malignancy: A single-center experience.

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 1,575 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 (>45ng/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.