Periodontitis, gum disease, is thought to contribute to a range of age-related conditions by allowing bacteria and bacterial products into the blood stream to provoke chronic inflammation. The risk of periodontitis is affected by the composition of the oral microbiome. Here, researchers show that the presence of some bacterial species is also correlated with risk of head and neck cancer. Chronic inflammation tends to produce a more hospitable environment for the growth of cancerous tissue.
Experts have long observed that those with poor oral health are statistically more vulnerable than those with healthier mouths to head and neck squamous cell carcinoma (HNSCC), a group that includes the most common cancers of the mouth and throat. While small studies have tied some bacteria in these regions (the oral microbiome) to the cancers, the exact bacterial types most involved had until now remained unclear.
Researchers analyzed data from three ongoing investigations tracking 159,840 Americans from across the country to better understand how diet, lifestyle, medical history, and many other factors are involved in cancer. Shortly after enrolling, participants rinsed with mouthwash, providing saliva samples that preserved the numbers and species of microbes for testing. Researchers then followed up for roughly 10 to 15 years to record any presence of tumors. The investigators analyzed bacterial and fungal DNA from the saliva samples. Then, they identified 236 patients who were diagnosed with HNSCC and compared the DNA of their oral microbes with that of 458 randomly selected study subjects who had remained cancer-free.
Of the hundreds of different bacteria that are routinely found in the mouth, 13 species were shown to either raise or lower risk of HNSCC. Overall, this group was linked to a 30% greater likelihood of developing the cancers. In combination with five other species that are often seen in gum disease, the overall risk was increased by 50%. This is the largest and most detailed analysis of its kind to date. It is also among the first to examine whether common fungi, organisms like yeast and mold that, along with bacteria, make up the oral microbiome, might play a role in HNSCC. The new experiments found no such role for fungal organisms.
Link: https://nyulangone.org/news/bacteria-involved-gum-disease-linked-increased-risk-head-neck-cancer
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