Diagnostic usefulness of tumor marker levels in pleural effusions of malignant and benign origin

Purpose: The aim of the present study was to determine the usefulness of simultaneous quantification of carbohydrate antigen 19.9 (CA 19.9), carbohydrate antigen 125 (CA 125), neuron specific enolase (NSE), mucinous-carcinoma-associated antigen (MCA), and ferritin in samples of pleural fluids (PF) in order to differentiate malignant from benign pleural effusions (PE). Patients and methods: A total of 61 PE were collected from patients with malignant or benign diseases. The diagnosis of PE was carried out cytologically or histologically by pleural biopsy. Tumor markers were determined in patients with benign or malignant diseases. CA 19.9, CA 125, NSE, and ferritin levels were quantified by the sandwich assay using the streptavidin method (ELISA). MCA was measured by employing a two-side solid phase enzyme immunoassay (EIA) method. PEs, either correctly or incorrectly identified as malignant or nonmalignant were defined as true positive (TP), false positive (FP), true negative (TN), and false negative (FN), the term 'positive' referring to histologically or cytologically proven malignant PE. Sensitivity (S), specificity (s), positive predictive value (PPV), and negative predictive value (NPV) were defined as diagnostic parameters. A cut-off value more than the nonmalignant group mean 2 standard deviation (SD) was considered as positive. Results: The calculated cut-off values were 352 U/ml for CA 125, 54 U/ml for CA 19.9, 555 ng/ml for ferritin, 11.1U/ml for MCA and 8.7 ng/ml for NSE. MCA was found to show the highest S (100%); CA 19.9 displayed the highest s (97%); CA 125, CA 19.9 and MCA showed the highest PPV (95%) and MCA had the highest NPV (100%). The combined measurement of MCA + CA 19.9 + CA 125 slightly increased the S, PPV and NPV. Conclusion: Our results imply that the co-measurement of MCA + CA 19.9 + CA 125 levels may further improve their diagnostic value in malignant PE compared with that of each tumor marker alone and may be useful in distinguishing malignant from benign PE