Preoperative Inflammatory Blood Indices as Prognostic Markers in Oral Squamous Cell Carcinoma: A Systematic Review and Meta-Analysis.

Oral squamous cell carcinoma (OSCC) prognosis remains limited by TNM staging alone. We conducted a systematic review and meta-analysis to evaluate preoperative neutrophil-to-lymphocyte (NLR), platelet-to-lymphocyte (PLR) and lymphocyte-to-monocyte (LMR) ratios as prognostic markers. We searched PubMed/MEDLINE, Scopus, Base, Google Scholar and ScienceDirect from inception to 30 May 2026. Eligible studies reported preoperative ratios and survival outcomes, namely, overall survival (OS), disease-specific survival (DSS) and disease-free survival (DFS), in surgically treated OSCC. Risk of bias was assessed with the QUIPS tool. Random-effects meta-analyses of multivariate hazard ratios (HRs) were primary; univariate data, heterogeneity, prediction intervals, sensitivity and subgroup analyses were also performed. Thirty-nine studies (12,153 patients; mostly East Asian retrospective cohorts) were included. Elevated NLR predicted worse overall survival (HR 1.51, 95% CI 1.32-1.73) and disease-specific survival (HR 2.00, 1.58-2.54). NLR also showed a significant association with DFS (HR = 1.47, 95% CI: 1.21-1.78), though the prediction interval crossed unity. PLR and LMR showed weaker, less consistent associations. Evidence was limited by predominant retrospective design, geographic concentration and variable cut-offs. Preoperative NLR is a reproducible, inexpensive prognostic biomarker that may complement TNM staging; standardized thresholds require prospective validation. The review was registered in PROSPERO; no specific funding was received.