Oral Health and the Oral Microbiome in Pancreatic Cancer: An Overview of Epidemiological Studies.

PURPOSE: The aim was to provide a cohesive overview of epidemiological studies of periodontal disease, oral microbiome profiles, and pancreatic cancer risk. DESIGN: A PubMed search of articles published in English through July 2017 with additional review of bibliographies of identified articles. RESULTS: Risk estimates for periodontal disease associated with pancreatic cancer consistently ranged from 1.5 to 2, aligning with a meta-analysis summary relative risk of 1.74. Analyses of antibodies to pathogenic and/or commensal oral bacteria in prediagnostic blood provided evidence that some oral bacteria and oral microbial diversity may be related to pancreatic cancer. CONCLUSIONS: Overall, the data present a plausible but complex relationship among pancreatic cancer, the oral microbiome, periodontal disease, and other risk factors that might be explained by systemic effects on immune and inflammatory processes. Larger comprehensive studies that examine serially collected epidemiological/clinical data and blood, tissue, and various microbial samples are needed to definitively determine how and whether oral health-related factors contribute to pancreatic cancer risk.