Validating a Panel of Salivary miRNA and Protein Biomarkers for the Early Detection of High-Risk Oral Potentially Malignant Disorders

Abstract

Background: Oral potentially malignant disorders (OPMDs) are precancerous oral lesions with variable risk of progression to oral squamous cell carcinoma, yet current assessment depends largely on biopsy-based histopathology, which is invasive and not ideal for repeated screening. Salivary molecular diagnostics offer a non-invasive alternative capable of detecting early biological changes associated with malignant potential. Objective: To assess the diagnostic performance of a combined salivary biomarker panel comprising miR-21, miR-31, miR-184, IL-8, and MMP-9 for differentiating patients with high-risk OPMDs from healthy controls. Methods: In this cross-sectional observational study, 84 participants were enrolled, including 44 patients with clinically and histopathologically confirmed OPMDs and 40 healthy controls. Unstimulated saliva samples were analyzed for miR-21, miR-31, and miR-184 expression by quantitative real-time polymerase chain reaction and for IL-8 and MMP-9 concentrations by enzyme-linked immunosorbent assay. Group comparisons, correlations, and receiver operating characteristic analyses were performed. Results: All three microRNAs and both proteins were significantly elevated in OPMD cases compared with controls (p < 0.001 for all). The strongest correlations were observed between miR-21 and IL-8 (r = 0.72) and between miR-31 and MMP-9 (r = 0.68). Individual biomarker AUCs ranged from 0.81 to 0.89, while the combined panel achieved an AUC of 0.94 (95% CI: 0.89-0.98), with sensitivity of 91.2% and specificity of 88.7%. Conclusion: The combined salivary biomarker panel demonstrated strong diagnostic accuracy for identifying high-risk OPMDs and supports the potential of saliva-based molecular profiling as a practical non-invasive adjunct for early oral precancer detection.