The Role of Salivary Biomarkers in Early Detection of Oral Precancerous Lesions

Background: Oral precancerous lesions are potentially malignant disorders that carry a high risk of transformation into oral cancer if not detected early. Conventional diagnostic methods rely on invasive biopsies, highlighting the need for reliable, non-invasive biomarkers. Salivary malondialdehyde (MDA), interleukin-6 (IL-6), and lactate dehydrogenase (LDH) reflect oxidative stress, inflammation, and tissue injury, respectively, and may serve as valuable diagnostic tools. Objectives: To measure and compare salivary levels of MDA, IL-6, and LDH between patients with oral precancerous lesions and individuals without such lesions, and to assess their diagnostic potential. Methods: A case-control study was conducted at the Oncology Center, Medical City, Baghdad, Iraq, between August 2024 and March 2025. A total of 102 participants were enrolled: 54 patients with clinically and histopathologically confirmed oral precancerous lesions and 48 lesion-free controls. Unstimulated saliva samples were collected under standardized conditions and analyzed for MDA, IL-6, and LDH levels using validated biochemical methods. Statistical analyses, including ROC curve evaluation, were performed to assess diagnostic accuracy. Results: Patients with oral precancerous lesions exhibited significantly higher salivary concentrations of MDA, IL-6, and LDH compared to negative cases (p < 0.05). ROC analysis demonstrated good diagnostic performance for all three biomarkers, with IL-6 showing the highest area under the curve, followed by MDA and LDH. No significant gender-based differences were observed in biomarker expression. Conclusion: Elevated salivary levels of MDA, IL-6, and LDH are strongly associated with oral precancerous lesions, suggesting their utility as non-invasive biomarkers for early detection. Incorporating these salivary assays into routine screening may facilitate timely intervention and reduce the progression to oral cancer.