DIAGNOSTIC UTILITY OF CANCER RATIO IN DIFFERENTIATING MALIGNANT FROM NONMALIGNANT PLEURAL EFFUSIONS: A RETROSPECTIVE STUDY

Abstract

Background:

Differentiating malignant pleural effusions (MPEs) from non-malignant effusions is crucial but the definitive diagnostic method is biopsy, which relies on histopathological examination. However, biomarker ratios, such as cancer ratio like serum LDH to pleural ADA (S-LDH:P-ADA), offer minimally invasive alternatives with promising potential.

Aim and Objectives:

This study aimed to evaluate the diagnostic utility of cancer ratio in distinguishing malignant from non-malignant pleural effusions (non-MPEs).

Materials and Methods:

Aretrospective analysis of patient recordsof 69 participants (18 MPE, 51 non-MPE) was conducted at Saveetha Medical College. Biomarker levels and ratios were calculated and analysed using ROC curve analysis and multivariate logistic regression.

Results:

P-LDH:S-CRP demonstrated the highest diagnostic accuracy (AUC = 0.874). Although S-LDH:P-ADA was not statistically significant, its predictive metrics (PPV = 38.7%, NPV = 86.5%, PLR = 1.893, NLR = 0.469) suggest potential with larger cohorts. Notably, combining biomarker ratios, particularly P-LDH:S-LDH and P-LDH:S-CRP, further improved diagnostic performance, yielding an AUC of 0.869, underscoring the added value of integrating multiple biomarkers in MPE differentiation.

Conclusion:

P-LDH:S-CRP and P-LDH:S-LDH ratios demonstrated superior diagnostic accuracy, improving sensitivity and specificity in differentiating malignant from non-malignant pleural effusions. Combining biomarker ratios enhanced diagnostic performance, supporting their role as non-invasive alternatives to traditional methods. Further validation in larger cohorts is warranted.