Risk of cancer in periodontal disease: an umbrella review of meta-analyses.

Objective: This study aims to summarize and appraise the credibility of existing epidemiological evidence on the association between periodontal diseases (PDs) and the risk of site-specific cancers. Methods: PubMed, Embase, and Cochrane Library were searched from inception to June 2026. Meta-analyses of observational studies investigating PDs and cancer risk were included. Each association was classified into five levels according to a predefined criterion, which included statistical significance, heterogeneity, sample size, and bias assessment. AMSTAR 2 was used to evaluate the quality of studies. Corrected covered area and the author's own meta-analysis were performed to ensure a rigorous methodology. Results: In total, 66 associations from 38 meta-analyses investigating 14 cancer types were appraised, including head and neck cancer (HNC), oral, lung, breast, esophageal, gastric, pancreatic, liver, colorectal, bladder, kidney, prostate, melanoma, and hematopoietic and lymphatic cancers. Among 23 main associations, highly suggestive evidence was identified in associations between PDs (odds ratio [OR], 2.42; 95% confidence interval [CI], 1.85-3.17) in HNC, and PDs in oral cancer (OR, 2.94; 95% CI, 2.13-4.07). Another seven associations were recommended as suggestive evidence (class III). Fourteen associations were classified as weak (class IV) or showing no significant evidence (class V). Conclusion: Associations between PDs and site-specific cancers demonstrated varying levels of evidence. This analysis highlighted strong correlations in HNC and oral cancer, while failing to show credible evidence for the remaining 12 cancers. Overall, our study yielded novel insights into oral health interventions, calling for the incorporation of periodontal health into public health policy. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/view/CRD42024585375, identifier CRD42024585375.