Salivary Biomarkers for Early Detection of Oral Squamous Cell Carcinoma: A Narrative Review

Oral squamous cell carcinoma (OSCC) contributes to nearly 90% of oral cancers and maintains a poor survival rate mainly due to diagnosis at an advanced stage.Early detection remains a major clinical challenge despite the easy accessibility of the oral cavity.In recent years, saliva has evolved as a potential, non-invasive diagnostic biofluid for the identification of OSCC-related biomarkers.Saliva contains a wide variety of biomolecules, including proteins, DNA, RNA, microRNAs, metabolites, cytokines, and extracellular vesicles, many of which depict tumor-associated molecular changes in them.This narrative review summarizes and evaluates current literature evidence on salivary biomarkers for the timely detection of OSCC, with a special focus on proteomic, genomic, transcriptomic, metabolomic, and inflammatory markers.Recent advances in analytical platforms such as mass spectrometry and polymerase chain reaction have enabled identification of several salivary biomarkers, including IL-6, IL-8, TNF-α, AZGP1, KLK1, BPIFB2, salivary mRNAs, and microRNAs, with diagnostic and prognostic relevance in OSCC.Limitations arise from incomplete biomarker validation, variation in saliva collection and analytical workflows, tumour heterogeneity, and restricted multicentric evidence.