Pleural fluid matrix metalloproteinase-9 levels and cancer ratio as diagnostic tools for malignant pleural effusion

Introduction. Malignant pleural effusion (PE) poses significant diagnostic and therapeutic challenges due to its diverse etiologies and variable clinical presentations. Accurate differentiation between malignant and non-malignant effusions is crucial for guiding appropriate treatment decisions and improving patient outcomes. Among the biomarkers studied for this purpose, matrix metalloproteinase-9 (MMP-9) in pleural fluid and the cancer ratio (CR) have shown promise in recent research. Material and metbods. This study used a non-randomized cross-sectional observational design, carried out at Saiful Anwar Hospital (January-June 2023), to determine the levels of MMP-9 and CR in pleural fluid in patients with malignant and non-malignant PE and to compare these levels between the two groups. Results. MMP-9 was higher in malignant PE compared to non-malignant (238.12 vs. 192.27, p < 0.05). CR in malignant PE was higher than in non-malignant PE (40.71 vs. 22.73, p < 0.05). AUC values for MMP-9 and CR were 0.543 (p = 0.025) and 0.788 (p = 0.000), respectively. The sensitivity and specificity of MMP-9 (cut off 112.5) were 57.6% and 63.6%, respectively, while CR (cut off 21.337) were 72.7% and 74.5%, respectively. A combination of MMP-9 > 122.5 and CR > 21.337 provided sensitivity of 45.45%, specificity of 87.27%, and diagnostic accuracy of 71.59% and turned out to be the diagnostic threshold value for the malignant group (p = 0.001) Conclusions. CR has higher sensitivity and accuracy compared to other biomarkers. The combination of Pleural Fluid MMP-9 and CR shows good specificity.