Omics-Derived Prognostic Biomarkers in Tongue Squamous Cell Carcinoma: A Systematic Review with Risk-of-Bias...

Tongue squamous cell carcinoma (TSCC) is clinically heterogeneous, and patients with a similar TNM stage can experience markedly different outcomes. We systematically reviewed omics-driven studies to identify prognostic TSCC biomarkers. Although fundamentally prognostic, we discussed their theoretical translational relevance regarding future clinical decisions-such as treatment stratification or surveillance intensity-while strictly framing them as preliminary, hypothesis-generating targets. PubMed, Scopus, Web of Science, and Cochrane were searched for original human studies published between 2014 and 2024 using high-throughput genomic or transcriptomic profiling. Study selection followed referred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), data were extracted with a structured workbook, and risk of bias was assessed using QUIPS and PROBAST, with reporting completeness appraised using REMARK. Seventeen studies were included, identifying 85 distinct biomarkers. Across biomarkers supported by multivariable overall survival analyses, higher-risk associations were reported for NELL2, PDE4D, CTTN, HBEGF, and CA9, whereas lower-risk associations were reported for AC139530.1, LINC01711, CCDC96, CYP2J2, and SPAG16. Recurrent biological themes included IL-17 signaling, ECM-receptor interaction, and focal adhesion. CA9 was the only biomarker reported in more than one included study, supporting its prioritization for validation. Although the evidence remains heterogeneous and largely hypothesis-generating, these markers may support the future validation of response-oriented therapeutic stratification in TSCC.