Oral bacteria may be biomarker to predict risk for head, neck cancers
Click Here to Manage Email Alerts
Key takeaways:
- Certain oral bacteria may increase or decrease risk for head and neck cancers.
- Bacteria associated with good oral hygiene appeared to protect against head and neck cancers.
Researchers have found evidence that the contents of an individual’s oral microbiome may be associated with their risk for head and neck cancers.
More than 20 bacterial species may increase or reduce the likelihood that someone will develop one of these malignancies, prospective study results showed.
“Bacteria that are associated with a healthy mouth are associated with a reduced risk for head and neck cancer, and those that are associated with periodontal disease are associated with an elevated risk,” Richard B. Hayes, DDS, MPH, PhD, professor in the department of population health at NYU Grossman School of Medicine, told Healio. “Hygiene practices such as tooth brushing, dental floss and regular visits to the dentist are a good thing to do — not only for your teeth, but also to control risk for head and neck cancer.”
Background and methods
Prior studies have shown smoking, alcohol and HPV all contribute to a person’s risk for head and neck squamous cell carcinoma.
Several decades ago, researchers investigating alcohol’s association found bacteria in the mouth could “metabolize alcohol to its carcinogenic form,” Hayes said.
“We’ve known for years that alcohol consumption is related to increased risk for head and neck cancer,” Hayes added, “but this research suggesting that bacteria in the mouth may be playing a role in this phenomenon really struck my curiosity.”
Hayes and colleagues first reviewed data from three cohorts of U.S. adults aged 50 to 74 years from the American Cancer Society Cancer Prevention Study II Nutrition Cohort, the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, and the Southern Community Cohort Study.
The analysis included 236 people who subsequently developed HNSCC (mean age, 60.9 years; 75.4% men) and a control group of 485 matched cancer-free individuals.
All adults had provided oral samples following an oral wash. All samples had been obtained years before any of the individuals received a head and neck cancer diagnosis.
“That’s a very strong design to rule out this idea that ‘the bacteria didn’t cause the disease, the disease caused the bacteria,’” Hayes said. “You wouldn’t know which was which if you just were collecting samples from people who already had the disease.”
Results and next steps
After a mean follow-up of 5.1 years, Hayes and colleagues found 22 species of bacteria in the oral microbiome that had associations with HNSCC.
Bacteria that increased the likelihood for disease development included Pyramidobacter piscolens (HR = 1.72; 95% CI, 1.03-2.87), Lactobacillus paracollinoides (HR = 1.5; 95% CI, 1.03-2.18) and Porphyromonas cangingivalis (HR = 1.42; 95% CI, 1.02-1.99).
A group of bacteria known as red and orange complexes — which had been identified as having an association with periodontal disease decades ago — also increased risk for HNSCC (HR = 1.06; 95% CI, 1-1.12).
Seven bacteria exhibited inverse associations with HNSCC risk, including Simonsiella muelleri (HR = 0.65; 95% CI, 0.51-.0.84), Prevotella salivae (HR = 0.72; 95% CI, 0.55-0.96) and Streptococcus sanguinis (HR = 0.77; 95% CI, 0.62-0.94).
“Streptococcus sanguinis is a bacteria that’s known to occur in greater abundance [among] people who have a good periodontal condition,” Hayes said. “That fits with the possibility of causal association — that bacteria associated with a healthy mouth are associated with a reduced risk for head and neck cancer, and those that are associated with periodontal disease, as indicated in the red and orange complex, are associated with an elevated risk.”
No fungal species had any links with HNSCC.
Researchers acknowledged study limitations, including its observational nature, which could lead to “unmeasured factors at study entry.”
“Future research is needed to investigate if bacteria like the red and orange complex cause cancer in disease models or are found in tumors themselves, and the mechanism behind bacteria’s association with risk for HNSCC”, Hayes said.
“Our goal now is to set up a study where we make a prediction model,” Hayes added. “If you could imagine someone comes into a clinic — 60 years of age or so — and you take [an oral] sample like this and do a microbiologic scan of their bacteria, and you have their history of alcohol use, tobacco use and so forth, that all can be put together to make a projection of their likelihood of developing head and neck cancer.”
For more information:
Richard B. Hayes, DDS, MPH, PhD, can be reached at richard.b.hayes@nyulangone.org.
Collapse
Click Here to Manage Email Alerts