Study finds link between oral bacteria and increased risk of esophageal cancer

Oral bacteria has been linked to a wide range of serious medial conditions, including pancreatic cancer, stroke and lung cancer. New research shows that oral bacteria may also be linked to esophageal cancer.

Esophageal cancer makes up about 1 percent of all cancers diagnosed in the United States. The American Cancer Society estimates that about 17,290 new esophageal cancer cases will be diagnosed in 2018.

While previous research has shown that periodontal disease caused by certain oral bacteria has been linked to several types of cancer, Jiyoung Ahn, an associate professor in the department of population health and the department of environmental medicine at NYU Langone Health in New York, wanted to investigate the connection between oral microbiota and the risk of esophageal adenocarcinoma (EAC) or esophageal squamous cell carcinoma (ESCC).

According to the study, Ahn and her colleagues collected oral wash samples from 122,000 participants in two large health studies: the American Cancer Society Cancer Prevention Study II Nutrition cohort and the National Cancer Institute Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. According to the research, in 10 years of follow-up, 106 participants developed esophageal cancer.

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In a prospective case-control study, the researchers extracted DNA and sequenced oral wash samples, which allowed them to compare the oral microbiomes of the esophageal cancer cases and the cancer-free cases. Certain bacteria types were found to be associated with a higher risk of esophageal cancer, such as the Tannerella forsythia bacteria, which was associated with a 21 percent increased risk of EAC. Another periodontal pathogen, Porphyromonas gingivitis, was associated with a higher risk of ESCC.

However, the researchers also discovered that a few types of oral bacteria were associated with a lower risk of EAC. Bacterial biosynthesis of carotenoids was also associated with protection against esophageal cancer, according to the study. Ahn told Science Daily that certain bacteria may actually have a protective effect, and future research on the topic is required.

The American Dental Association says additional research is needed to examine whether certain bacteria could play a role in preventing esophageal cancer.

“The study underscores the importance of taking care of your teeth and gums,” the ADA says in a statement. “We know for sure that good dental hygiene - brushing your teeth twice a day with a fluoride toothpaste, cleaning between your teeth once a day, eating a healthy diet and seeing your dentist regularly - helps reduce the population of gum disease-causing bacterial species in the mouth, among which were the microbes found by the study to be associated with higher rates of esophageal cancer.”

This isn’t the first time research has shown a link between oral bacteria and esophageal cancer. In 2016, researchers from the University of Louisville School of Dentistry examined the relationship between a bacterial species that causes gum disease and esophageal cancer. In a study of 130 patients, the researchers discovered that 61 percent of patients with esophageal cancer had the bacteria present.

According to a recent report by the Centers for Disease Control and Prevention, 47.2 percent of adults ages 30 and older have some form or periodontal disease. Periodontal disease increases with age, and the condition is more common in men than women. In order to prevent periodontal disease, the American Academy of Periodontology recommends regular tooth brushing and flossing, swishing with mouthwash, and consulting with a dental professional or periodontist about your risk factors.

The full study, titled “Oral Microbiome Composition Reflects Prospective Risk for Esophageal Cancers,” appeared in Cancer Research, a journal of the American Association for Cancer Research.