Can bacteria in my mouth change as my oral squamous cell carcinoma gets worse?
Your mouth contains hundreds of bacterial species. When you have oral squamous cell carcinoma (OSCC), the balance of these bacteria can change. Studies suggest that as the cancer gets worse, the types and amounts of bacteria in your mouth may shift. For example, some bacteria become more common in early stages, while others decrease in advanced disease. These changes may be linked to tumor growth and inflammation.
What the research says
A 2024 narrative review found that Veillonella, a common oral bacterium, shows a dynamic and stage-dependent shift during oral carcinogenesis. Several studies report enrichment of Veillonella in early tumorigenesis and oral potentially malignant disorders, but reduced levels in advanced OSCC 2. This suggests that the bacterial community changes as the cancer progresses.
A 2023 study analyzed the salivary microbiome of OSCC patients before and after treatment. It found that the microbial profiles of OSCC patients differed from healthy controls, and that treatment (surgery and adjuvant therapy) further altered the microbiome 9. This indicates that both the cancer itself and its treatment can change your oral bacteria.
A 2024 systematic review of 27 studies confirmed significant changes in microbial composition between OSCC patients and controls. It noted a predominance of certain phyla associated with inflammation that may help tumor progression. The review also highlighted that microbial profiles vary depending on the stage of the disease 11.
Another review examined Helicobacter pylori and found contradictory results regarding its association with OSCC, so no clear conclusion could be drawn 10. However, the overall evidence points to a complex relationship between the oral microbiome and OSCC, with bacterial shifts occurring as the disease advances.
What to ask your doctor
- Could changes in my mouth bacteria affect my cancer or treatment?
- Are there any tests to monitor my oral microbiome during treatment?
- Should I consider probiotics or other ways to support a healthy mouth microbiome?
- How might treatments like surgery or radiation change my oral bacteria?
- Can you refer me to a specialist who studies the oral microbiome in cancer?
This question is drawn from common patient questions about this topic and answered using cited medical research. We do not provide individualized advice.