Mouth Bacteria Linked to Cancer – New Research Discovery
Table of Contents
published September 20, 2025
For decades, the mouth has been recognized as a potential entry point for carcinogens – substances that can cause cancer - through tobacco and alcohol use. However,recent research is revealing a far more complex relationship,demonstrating that the oral microbiome,the community of microorganisms living in our mouths,may actively contribute to cancer development and progression,even independently of these known risk factors. This finding, published in September 2024, is prompting a re-evaluation of oral health’s connection to systemic diseases.
How the Oral Microbiome Influences Cancer
Researchers at the University of Helsinki, led by Dr. Timo Sorsa, have identified specific bacterial enzymes within the oral microbiome that can directly promote cancer. Specifically, they’ve focused on enzymes that modify proteins, a process called protein arginine deiminase (PAD). These PAD enzymes, produced by certain bacteria like Porphyromonas gingivalis, are known to contribute to periodontitis – gum disease – but their impact extends far beyond the gums.
The study, detailed in the journal Oncotarget, found that PAD enzymes can modify proteins in ways that encourage cancer cell growth, invasion, and metastasis. This isn’t limited to oral cancers; the research suggests these enzymes can impact cancers elsewhere in the body. The team demonstrated that PAD enzymes can activate the epidermal growth factor receptor (EGFR), a key signaling pathway involved in the development of several cancer types, including head and neck cancers. National Center for Biotechnology Details provides further details on EGFR signaling.
Beyond Head and Neck Cancers: A Systemic connection
While the initial research focused on head and neck cancers, the implications are much broader. The study showed that PAD enzymes can promote the growth of several cancer cell lines in vitro (in a laboratory setting), suggesting a potential role in cancers of the lung, colon, and potentially others.This is because the enzymes and the bacteria that produce them can enter the bloodstream and travel to distant sites in the body.
Dr. Sorsa’s team also investigated the link between oral bacteria and cancer in a cohort of over 2,000 individuals. They found a statistically significant correlation between the presence of specific PAD-producing bacteria and an increased risk of developing cancer, even after accounting for conventional risk factors like smoking and alcohol consumption. This suggests that the oral microbiome is an self-reliant risk factor for cancer.
What This Means for Your Health
This research doesn’t mean everyone with gum disease will develop cancer. Though, it underscores the critical importance of maintaining good oral hygiene. Regular brushing, flossing, and professional dental cleanings can help control the growth of harmful bacteria and reduce the levels of PAD enzymes in the mouth.
Researchers are now exploring potential therapeutic strategies to target PAD enzymes and disrupt their pro-cancer effects. These include developing specific inhibitors of PAD enzymes and exploring ways to modulate the oral microbiome to promote a healthier balance of bacteria. Further research is needed to fully understand the complex interplay between the oral microbiome and cancer,but this discovery represents a significant step forward in our understanding of cancer development and prevention.The National Cancer Institute offers comprehensive information on cancer prevention and treatment.