Shared Genetic Risk Factors Between Periodontal Disease and Colorectal Cancer: A Scoping Review Protocol
Sydnie Zuckerman1, Matan Tordjman1, Igor Karp2, Amal Idrissi Janati1
1Faculty of Dentistry and Oral Health Sciences, McGill University, 2Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, Western University.
Colorectal cancer (CRC) continues to be ranked as the third most prevalent form of cancer both in Canada and globally. In 2023, it was estimated that 24,100 Canadians will be diagnosed with colorectal cancer. Representing 10% of all new cancer cases. Observational studies indicate that patients who have periodontal disease (PD) may increase their risk of developing CRC. This connection is thought to occur due to the spread of periodontopathogenic bacteria and their harmful substances to the colon, along with the circulation of chronic inflammation mediators throughout the body. Furthermore, it has been proposed that PD and CRC share common genetic factors, such as polymorphisms in genes that play a role in the immune system, potentially contributing to the link between these two diseases. As of now, these shared genetic markers have not been specifically identified, which poses a challenge for observational studies aiming to understand the relationship between PD and CRC fully. Research to date has separately explored genetic polymorphisms with either PD or CRC but has not simultaneously examined their association with both diseases. Therefore, this scoping review aims to identify the genetic polymorphisms associated to both periodontal disease and colorectal cancer. This scoping review will follow the methodological framework for scoping reviews provided by the Joanna Briggs Institute. The checklist from the Preferred Reporting Items for Systematic Reviews and Meta – Analyses (PRISMA) extension for Scoping Reviews will serve as a guide to ensure consistent reporting. The review will scrutinize published research articles where the authors discuss genetic polymorphisms in relation to PD and / or CRC, which will be considered for inclusion. MEDLINE, EMBASE, Web of Science, and Cochrane Database of Systematic Reviews will be searched using a comprehensive search strategy and manual screening of references, with no restrictions applied for date of publication. Two reviewers will independently identify eligible studies and extract the data from the included studies. Original, comparative studies that reported results on genetic polymorphisms and PD and / or CRC will be included in the review. The extracted information will include authors, country, year of publication, aim of the study, study design, sample size, study participants’ characteristics, the outcome (PD, CRC, or both) and the associated gene / polymorphism(s) as well as any additional findings. Findings will be presented in tabular form and a narrative description of the evidence. Outcomes from various observational studies indicate common genetic risk factors among PD and CRC; although, the shared genetic polymorphisms between the two conditions is yet to be examined. The results will likely display distinctive polymorphisms associated with periodontal disease and likewise for colorectal cancer. These results could provide a better understanding of the relationship between PD and CRC, and enable future observational studies to also control for genetic factors in addition to other known confounders of the association between PD and CRC.