STATH encodes statherin, a low-molecular-weight acidic phosphoprotein secreted in saliva with critical roles in oral homeostasis and health. The protein functions primarily to inhibit precipitation of calcium phosphate salts in the supersaturated salivary environment, thereby stabilizing saliva composition 1. Additionally, statherin modulates hydroxyapatite crystal formation on tooth surfaces, contributing to enamel integrity and structural maintenance. As part of the salivary host defense system, statherin exhibits antimicrobial properties and helps maintain oral microbial balance 2. Statherin belongs to an evolutionarily conserved gene family alongside histatins (HIS1, HIS2), sharing similar gene structures but exhibiting accelerated coding sequence divergence 1. The protein's saliva-specificity makes it a valuable forensic and diagnostic marker; STATH expression reliably identifies saliva in body fluid analysis and forensic investigations 3 4 5. Clinically, STATH downregulation is significantly associated with head and neck squamous cell carcinoma (HNSCC), correlating with poor prognosis and reduced overall survival, particularly in HPV-positive patients 2. The suppression likely reflects tumor-driven remodeling of the salivary microenvironment, weakening host oral defenses. STATH shows potential as a noninvasive diagnostic and prognostic biomarker in HNSCC, with expression correlated to immune infiltration patterns.