Pleural fluid carbohydrate antigen 72-4 and malignant pleural effusion: a diagnostic test accuracy study.

Abstract

The prognosis of malignant pleural effusion (MPE) is poor. A timely and accurate diagnosis is the prerequisite for managing MPE patients. Carbohydrate antigen 72-4 (CA72-4) is a diagnostic tool for MPE. We aimed to evaluate the diagnostic accuracy of pleural fluid CA72-4 for MPE. A prospective, preregistered, and double-blind diagnostic test accuracy study. We prospectively enrolled participants with undiagnosed pleural effusions from two centers in China (Hohhot and Changshu). CA72-4 concentration in pleural fluid was measured by electrochemiluminescence. Its diagnostic accuracy for MPE was evaluated by a receiver operating characteristic (ROC) curve. The net benefit of CA72-4 was determined by a decision curve analysis (DCA). In all, 153 participants were enrolled in the Hohhot cohort, and 58 were enrolled in the Changshu cohort. In both cohorts, MPE patients had significantly higher CA72-4 levels than benign pleural effusion (BPE) patients. At a cutoff value of 8 U/mL, pleural fluid CA72-4 had a sensitivity, specificity, and area under the ROC curve (AUC) of 0.46, 1.00, and 0.79, respectively, in the Hohhot cohort. In the Changshu cohort, CA72-4 had a sensitivity, specificity, and AUC of 0.27, 0.94, and 0.86, respectively. DCA revealed the relatively high net benefit of CA72-4 determination. In patients with negative cytology, the AUC of CA72-4 was 0.67. Pleural fluid CA72-4 helps differentiate MPE and BPE in patients with undiagnosed pleural effusions.