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

Pleural effusion is a common diagnostic problem. The analysis of serum and body fluids for tumor markers has been intensively applied to clinical diagnosis. The aim of the present study was to determine the usefulness of simultaneous quantification of carbohydrate antigen 19.9, carbohydrate antigen 125, neuron specific enolase, mucinous-carcinoma-associated antigen, and ferritin in samples of pleural fluids in the malign pleural effusion and its differentiation from benign effusions. A total of 61 pleural effusions were collected from the patients, who were subjected either to simple needle aspiration or to tube drainage for the diagnosis of pleural effusion. Tumor markers were determined in benign patient groups with nonspecific pleurisy, tuberculous pleurisy, empyema, congestive heart failure and in malignancy groups consisting of adenocarcinoma, small cell lung carcinoma, mesothelioma, epidermoid lung cancer. The tumor markers CA-19.9, CA-125, NSE, and ferritin levels were quantified by the sandwich assay using the streptavidin technology of ELISA in an ES-300 Boehringer-Mannheim analyser. MCA was measured by employing a two-side solid phase EIA method. MCA measurements were done by the Cobas-Core. For all patients, the effusions correctly or incorrectly identified by the different procedures as being malignant or nonmalignant are defined as true positive, false positive, true negative, and false negative, the term 'positive' referring to histologically proven malignant pleural effusion while nonmalignant effusions are referred to as 'negative'. Therefore, sensitivity, specificity, positive predictive value, and negative predictive value were defined as diagnostic parameters. The cut-off values calculated were 352 U/ml for CA-125, 54 U/ml for CA-19.9, 555 for ferritin, 11.1 for MCA and 8.7 for NSE. In our study, the highest sensitivity is found to be MCA with 100%; specificity, CA-19.9 with 97%; PPV, CA-19.9 and MCA with 95% and NPV, MCA with 100%. Our data imply that the co-measurement of MCA+CA-19.9+CA-125 levels may further improve their diagnostic value in malignant pleural effusion compared with that of each tumour marker alone and may be useful in distinguishing malignant from benign pleural effusions.