Cytokeratin 19 fragment/carcinoembryonic antigen ratio in pleural effusion is a useful marker for detecting malignant pleural mesothelioma.

BACKGROUND The clinical utility of tumour markers in pleural effusion is still controversial with regard to the efficient detection of malignant pleural mesothelioma (MPM). PATIENTS AND METHODS The levels of carcinoembryonic antigen (CEA) and cytokeratin 19 fragment (CYFRA 21-1) were retrospectively studied in pleural effusion of unknown origin in patients who had undergone medical thoracoscopy under local anaesthesia. RESULTS The study included 134 patients (103 men and 31 women); among them, 33 had MPM. The level of pleural effusion CYFRA 21-1 and the CYFRA 21-1/CEA ratio were significantly different between MPM and other diseases (p<0.01). The sensitivity and specificity of the pleural effusion CYFRA 21-1/CEA ratio were 84.8% and 80.2%, respectively, when the CYFRA 21-1/CEA ratio cut-off value determined by receiver operating characteristic curve analysis was 19.1. CONCLUSION MPM should be suspected when the CYFRA 21-1/CEA ratio in pleural effusion is greater than 19.1.