Diagnostic Accuracy of CYFRA21-1 in the Differential Diagnosis of Pleural Effusions

Abstract

Background/Aim: Approximately 20% of pleural effusions are associated with cancer; about 50% require invasive procedures to perform diagnosis. Determination of the concentration of soluble cytokeratin 19-fragments (CYFRA21-1) may help identify patients with malignant effusions. However, pathologies other than cancer can increase its concentration. The identification of these possible false positives with routine tests CRP, ADA, % polymorphonuclear cells (PN) may improve diagnostic accuracy. This study aimed to determine the diagnostic accuracy of CYFRA21-1 in the detection of malignant pleural effusions and the possible false positives. Materials and Methods: Analysis of CYFRA21-1, adenosine deaminase (ADA), C-reactive protein (CRP), and the percentage of polymorphonuclear leukocytes (PN%) in the fluid from 643 consecutive undiagnosed pleural effusions was performed. Results: CYFRA21-1 showed 38.7% sensitivity and 97.3% specificity at 175 ng/ml cut-off. Effusions not suspicious of a false-positive showed 39.0% sensitivity and 98.2% specificity, while effusions suspicious of false positive showed lower sensitivity (36.4%) and specificity (95.0%). Conclusion: The diagnostic accuracy of CYFRA21-1 in pleural effusions can be improved by classification according to the possibility of false positives.