Metabolic syndrome confers a higher risk of oral cancer: a meta-analysis.

BACKGROUND: Metabolic syndrome (MetS) has been implicated in the development of several malignancies, but its association with oral cancer (OC) remains uncertain. This meta-analysis aimed to evaluate the association between MetS and the risk of incident OC. METHODS: PubMed, Embase, and Web of Science were systematically searched from inception to May 11, 2026. Longitudinal cohort studies comparing the incidence of OC between adults with and without MetS were included. Hazard ratios (HRs) and 95% confidence intervals (CIs) were pooled using random-effects models accounting for potential heterogeneity. RESULTS: Four cohort studies comprising 6,370,396 participants and 4,539 incident OC cases were included. One study reported sex-specific estimates, resulting in five datasets for the primary meta-analysis. Overall, MetS was associated with a significantly increased risk of OC (HR: 1.12, 95% CI: 1.04-1.20; p = 0.001), with low heterogeneity (I² = 8%). Leave-one-out sensitivity analyses yielded consistent results (pooled HRs: 1.08-1.16). Subgroup analysis showed no significant difference between men and women (HR: 1.14 vs. 1.02; p for subgroup difference = 0.35). Exploratory analyses indicated that hypertriglyceridemia (HR: 1.07, 95% CI: 1.00-1.14; p = 0.04) and hyperglycemia (HR: 1.22, 95% CI: 1.10-1.36; p < 0.001) were significantly associated with increased OC risk, whereas central obesity, low high-density lipoprotein cholesterol, and hypertension were not. CONCLUSIONS: Current longitudinal evidence suggests that MetS is associated with a modest but significant increase in the risk of incident OC. Findings for individual MetS components are exploratory and hypothesis-generating. SYSTEMATIC REVIEW REGISTRATION: https://www.crd.york.ac.uk/PROSPERO/, identifier CRD420261432959.