Liquid biopsy in oral cancer: Current perspectives – A narrative review

Introduction: Liquid biopsy is a minimally invasive diagnostic method that analyzes tumor-derived components in various body fluids, including blood, urine, saliva etc. By enabling repeated sampling, this technique allows real-time assessment of tumor heterogeneity, disease progression, and response to treatment. This review discusses the current understanding and clinical applications of liquid biopsy, particularly in oral cancer, and other systemic diseases. Methods: For this review, a narrative literature search was carried out using PubMed, Google Scholar, and Scopus and later relevant articles that focused on circulating biomarkers, different liquid biopsy techniques, and their clinical applications were selected and analyzed. Results: Key biomarkers include circulating tumor DNA (ctDNA), cell-free DNA (cfDNA), circulating tumor cells (CTCs), extracellular vesicles (exosomes), microRNAs (miRNAs), and tumor-educated platelets. ctDNA shows high specificity for mutation detection, while CTCs are associated with disease stage and prognosis but have limited sensitivity in early disease. Exosomes and miRNAs are linked to tumor-related molecular changes, whereas cfDNA and cfRNA provide genetic and epigenetic data. In oral cancer, salivary miRNAs and cfDNA are useful for non-invasive detection and monitoring. Discussion: Liquid biopsy improves precision diagnostics through repeatable sampling, minimal invasiveness, and continuous monitoring of molecular changes. Future directions include early cancer detection, incorporation of artificial intelligence, and expanded use in dental and systemic diseases. Standardization of protocols and improved analytical sensitivity are essential for wider clinical adoption.