Periodontal disease was associated with an increased risk of two precursors of colorectal cancer, according to results of a study published by Lo et al in Cancer Prevention Research.

“Periodontal disease is prevalent among adults, with periodontitis affecting more than 40% of the U.S. population,” explained the study’s lead author, Mingyang Song, MD, ScD, Assistant Professor of Clinical Epidemiology and Nutrition at the Harvard T.H. Chan School of Public Health.

Previous research has explored associations between periodontal disease and several cancer types, including breast, head and neck, and pancreatic cancers, but little research has examined potential associations between periodontal disease and colorectal cancer.

Study Details

In this study, researchers examined two types of colorectal neoplasms: serrated polyps and conventional adenomas, both of which frequently develop into colorectal cancer. Contributing author Chun-Han Lo, MD, MPH, a postdoctoral research fellow in the Clinical and Translational Epidemiology Unit and Division of Gastroenterology at Massachusetts General Hospital and Harvard Medical School, explained that serrated polyps are often characterized by mutations in the gene BRAF and microsatellite instability, while adenomas are characterized by mutations in the gene KRAS and chromosomal instability.  

The researchers collected data on periodontal disease and tooth loss from the Nurses’ Health Study and the Health Professionals Follow-up Study. Study enrollees reported whether they had ever been diagnosed with colorectal polyps or adenomas, and the researchers confirmed diagnoses via medical records.

In all, the study enrolled 42,486 people and used data from 84,714 person-endoscopies.

Results

Overall, those who had periodontal disease had a 17% higher risk of developing serrated polyps and an 11% higher risk of developing conventional adenomas. Those who had lost four or more teeth had a 20% higher risk of developing serrated polyps.  

Among participants with periodontal disease, the more teeth a person lost, the higher their risk of advanced conventional adenomas. Those who had periodontal disease and had lost one to three teeth had a 28% higher chance of developing advanced conventional adenomas, while those who had periodontal disease and lost four or more teeth had a 36% higher risk.

The researchers pointed out that the association between tooth loss and small serrated polyps and advanced conventional adenomas was not observed for large serrated polyps. Dr. Song said this finding was somewhat surprising, as large serrated polyps are known predictors of cancer risk. He said the small sample size of large serrated polyps may have limited the statistical power for detecting that association.

While smoking is a known cause of both periodontal disease and colorectal cancer, the authors noted that even nonsmokers with tooth loss had higher rates of serrated polyps and conventional adenomas.

“Having ever been diagnosed with periodontal disease puts a person at risk of colorectal cancer precursor lesions, some of which may eventually lead to colorectal cancer,” explained Dr. Song. “Regular screening colonoscopy and lifestyle modifications are particularly important in this population.”

The authors said these study results contribute to a growing body of research on how the oral microbiome may influence the development of cancer.

“The oral cavity harbors a wide array of microbial communities,” said Dr. Song. “Various factors—including poor oral hygiene, genetic susceptibility, smoking, diabetes, and obesity—can result in an excess of oral pathogens that may induce host inflammation and immune dysregulation.”

Dr. Song said the results of this study, combined with previous research linking periodontal disease to some types of cancer, reinforce the importance of good oral health to ensure a healthy oral microbiome. Also, people who have experienced tooth loss may benefit from more intensive cancer screening measures.

Some of the study’s limitations include the self-reporting of tooth loss and the small sample size for large serrated polyps. Also, most respondents were White, and the authors cautioned that results should be confirmed in more diverse populations.

Disclosure: This study was funded by grants from the National Institutes of Health, the American Institute for Cancer Research, the American Cancer Society, the Project P Fund for Colorectal Cancer Research, the Bennett Family Fund, and the Entertainment Industry Foundation through Colorectal Cancer Research Alliance. For full disclosures of the study authors, visit cancerpreventionresearch.aacrjournals.org.