Salivary Biomarkers and Their Link to Oncogenic Signaling Pathways in Oral Squamous Cell Carcinoma: Diagnostic and Translational Perspectives in a Narrative Review

This narrative review examines recent advances in salivary biomarkers for oral squamous cell carcinoma (OSCC), a major subtype of oral cancer with persistently low five-year survival rates due to delayed diagnosis. Saliva has emerged as a noninvasive diagnostic medium capable of reflecting both local tumor activity and systemic physiological changes. Various salivary biomarkers, including microRNAs, cytokines, proteins, metabolites, and exosomes, have been linked to oncogenic signaling pathways involved in tumor progression, immune modulation, and therapeutic resistance. Advances in quantitative polymerase chain reaction, mass spectrometry, and next-generation sequencing have enabled comprehensive biomarker profiling, while point-of-care detection systems and saliva-based omics platforms are accelerating clinical translation. Remaining challenges include variability in salivary composition, lack of standardized collection protocols, and insufficient validation across large patient cohorts. This review highlights the mechanistic relevance, diagnostic potential, and translational challenges of salivary biomarkers in OSCC.