A recent study has found that more than a dozen bacterial species in the mouth are linked to a 50% higher risk of developing head and neck squamous cell carcinoma (HNSCC). Some of these bacteria had previously been connected to periodontal disease, a serious gum infection that can damage the jawbone and surrounding tissues. Poor oral health has long been associated with a greater vulnerability to HNSCC, the most common form of mouth and throat cancers. However, the specific bacteria involved were unclear until now.
Researchers from NYU Langone Health and the Perlmutter Cancer Center conducted an analysis of oral microbes from healthy individuals, revealing that 13 bacterial species were either associated with an increased or decreased risk of HNSCC. Collectively, these bacteria contributed to a 30% higher likelihood of developing the cancer. When combined with five other bacteria commonly linked to gum disease, the risk jumped to 50%.
According to Soyoung Kwak, Ph.D., the study’s lead author, the findings offer new insights into how the oral microbiome is connected to head and neck cancers. These bacteria could potentially serve as biomarkers to help identify individuals at higher risk. The team had previously identified certain bacteria in tumor samples, and in 2018, they explored how microbes in healthy individuals could contribute to future cancer risk.
Their latest research, published on Sept. 26, is the most comprehensive analysis of its kind and one of the first to examine the role of fungi in the oral microbiome. The study found no link between fungi and HNSCC.
As reported by medicalxpress.com, the research involved analyzing data from over 159,000 Americans, collected through studies like the American Cancer Society Cancer Prevention Study II, the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, and the Southern Community Cohort Study. Participants provided saliva samples, which were used to assess their oral bacteria. The researchers then tracked cancer diagnoses over 10 to 15 years. By comparing the microbiomes of 236 individuals with HNSCC to 458 cancer-free participants, they found correlations between certain bacteria and cancer risk, while controlling for factors such as age, smoking, and alcohol use.
Co-senior author Richard Hayes, DDS, MPH, Ph.D., emphasized the importance of good oral hygiene, suggesting that brushing and flossing might help lower the risk of both periodontal disease and head and neck cancers. However, the study only established associations, not a direct cause-and-effect relationship, which will require further investigation. The next step, according to co-senior author Jiyoung Ahn, Ph.D., is to understand the mechanisms by which these bacteria contribute to cancer and how interventions might help reduce the risk.
Despite the concerning findings, Ahn noted that head and neck cancers remain relatively uncommon.