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 elision CYFRA 21-1/CEA ratio were 84.8% and 802%, 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.