Carcinoembryonic antigen in pleural effusions. Diagnostic value in malignant mesothelioma.

The usefulness of the determination of carcinoembryonic antigen (CEA) in pleural effusion was assessed as an aid to the diagnosis of malignant mesothelioma. The concentration of CEA was determined by radioimmunoassay (RIA) in pleural fluid of 213 adult patients, of which 140 had malignant pleural disease and 73 had nonmalignant pleural disease. Pleural fluid CEA (PF CEA) was lower than 12 ng/ml in all 15 mesotheliomas. The statistical probability of a mesothelioma associated with PF CEA greater than 15 ng/ml was found to be zero. The CEA assay in pleural effusion proved to be a valuable adjunct to other diagnostic procedures in differentiating the malignant mesothelioma from metastatic serosal spread.