The Oral Microbiome and Cancer: How Are They Related?(Post #14)

Welcome back to the Spiramen Founder's Blog! This week, we will be discussing the relation between oral cancer and the oral microbiome.

When we usually think of oral cancer, we assume it is casued by tobacco, alcohol, or an HPV infection. However, an emerging factor is the oral microbiome.

First, let's understand what the oral microbiome is:

• a community of bacteria, fungi, and microorganisms in the mouth

• contains hundreds of different microbial species

• the microbiome is balanced in healthy individuals

• it works to protect us against harmful pathogens and support our digestion system

• it can also help with our immune system work well

  
  

What we're learning now is that cancer is not caused only due to external habits, but also internal microbial balance. When the microbiome is disrupted or unbalanced, this is called dysbiosis. What scientists have found is that dysbiosis is

linked to multiple diseases, including cancer.

Recent studies have shown that certain bacteria are found across a wide range of oral cancer patients. Specific patterns in these patients' oral microbiomes have also been found. Some frequently observed species in oral cancer patients are:

• Fusobacterium nucleatum

• Porphyromonas gingivalis

These bacteria have been found to promote inflammation and disrupt normal cell processes (a key part of tumor formation!) These bacteria have been found in much high concentrations in tumor tissues vs. in healthy tissues

But how exactly do these bacteria lead to cancer? Scientists have found a few reasons:

• They cause chronic inflammation

  • Constant immune activation damages cells

• They increase toxin production:

  • The bacteria release harmful byproducts, and therefore increase toxin production

• They cause DNA damage

  • This damage increases mutation rates in oral cells, which a clear path to cancer

• Ability to evade immune system

  • They alter immune response, allowing abnormal (tumor) cells to survive

• They conduct "tumor promotion"

  • These bacteria create an environment favorable for cancer growth

Due to this relation between the oral microbiome and oral cancer, the microbiome can act as an early warning system for people. Detecting changes in a person's oral bacterial composition (through saliva testing) can tell people they are developing or have a risk of developing cancer. This has the potential to save so many lives!

To keep our oral microbiome healthy, there are a few measures we can take. Avoiding smoking, alcohol consumption, maintaining good oral hygiene (brush and floss!), and eating less sugary food are some of these measures.

This relation between microbiome and oral cancer is being implemented in emerging technology like saliva-based diagnostic tests (check previous lollipop post for an example!) If changes in microbiome are found early, it can help dictors predict cancer too. It may also help monitor potential recurrences.

However, some limitations exist. Every individual's microbiome varies, so setting a standard for a universal microbiome that is a sign of cancer is difficult. For this, researchers will need to compile a lot of diverse data and test their diagnostic technology, which tends to take many years.

In the future, we may be able to create cancer therapies that target the oral microbiome (probiotics/antimicrobial treatments) or create preventative strategies to fix the microbiome before cancer even develops!

Thanks for reading this week's post! See you again next week.

Information Citations:

Irfan, Muhammad, et al. “The Oral Microbiome and Cancer.” Frontiers in Immunology, 2020. https://pmc.ncbi.nlm.nih.gov/articles/PMC7645040/

“New Research Links Mouth Cancer to Oral Microbiome Changes.” American Society for Microbiology, 2025. https://asm.org/press-releases/2025/january/new-research-links-mouth-cancer-to-oral-microbiome

“Oral Microbiome-Derived Biomarkers for Non-Invasive Diagnosis of Head and Neck Squamous Cell Carcinoma.” Nature (npj Biofilms and Microbiomes), 2025. https://www.nature.com/articles/s41522-025-00708-8

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Image Citations:

Dentistry. “Advancing an Understanding of the Oral Microbiome,” Dentistry.co.uk, 27 Sept. 2021, dentistry.co.uk/2021/09/27/advancing-an-understanding-of-the-oral-microbiome/.