Bottom Line: An analysis of bacteria present in the mouth showed that some types of bacteria that lead to periodontal disease were associated with higher risk of esophageal cancer.
Journal in Which the Study was Published: Cancer Research, a journal of the American Association for Cancer Research.
Author: Jiyoung Ahn, PhD, an associate professor and associate director for population science at the Laura and Isaac Perlmutter Center at NYU Langone Health in New York.
Background: Esophageal cancer is the eighth most common cancer and the sixth leading cause of cancer death worldwide, Ahn said. Because the disease is often not discovered until it has reached an advanced stage, five-year survival rates range from about 15 to 25 percent worldwide.
"Esophageal cancer is a highly fatal cancer, and there is an urgent need for new avenues of prevention, risk stratification, and early detection," Ahn said.
Previous research has shown that periodontal disease caused by certain oral microbiota has been associated with several types of cancer, including oral and head and neck cancers. This study examined whether oral microbiota were associated with subsequent risk of esophageal adenocarcinoma (EAC) or esophageal squamous cell carcinoma (ESCC).
How the Study Was Conducted and Results: Ahn and colleagues collected oral wash samples from 122,000 participants in two large health studies: the National Cancer Institute Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial and the American Cancer Society Cancer Prevention Study II Nutrition cohort.
In 10 years of follow-up, 106 participants developed esophageal cancer. In a prospective case-control study, the researchers extracted DNA and sequenced oral wash samples, allowing researchers to compare the oral microbiomes of the esophageal cancer cases and the cancer-free cases.
Certain bacteria types were associated with higher risk of esophageal cancer. For example, higher levels of the Tannerella forsythia bacteria were associated with a 21 percent increased risk of EAC. The bacteria Porphyromonas gingivalis was associated with a higher risk of ESCC. Both species of bacteria are linked with common gum disease, Ahn noted.
The study showed that a few types of oral bacteria were associated with lower risk of esophageal cancer. For example, the Neisseria bacteria was associated with lower risk of EAC.
Author's Comments: Ahn said the finding on Neisseria indicates that certain bacteria may have a protective effect, and future research could potentially examine whether these bacteria could play a role in preventing esophageal cancer.
"Our study indicates that learning more about the role of oral microbiota may potentially lead to strategies to prevent esophageal cancer, or at least to identify it at earlier stages," Ahn said. "The next step is to verify whether these bacteria could be used as predictive biomarkers."
Ahn added that the study confirms that good oral health, including regular tooth brushing and dental visits, is an important way to guard against periodontal disease and the growing list of health conditions associated with it.
Study Limitations: The study's primary limitation is that the researchers did not have complete information on the participants' oral health. Therefore, they could not determine whether the presence of pathogens was enough to affect esophageal cancer risk, or whether full-blown periodontal disease was the risk factor.