In recent years, biomedical research has revealed an increasingly close connection between oral health and systemic diseases, opening up unprecedented possibilities in oncology as well. One of the most debated correlations is between colorectal cancer and the presence of the bacterium Fusobacterium nucleatum , a microorganism often found in dental plaque and in patients with periodontal disease. Studies conducted by international institutions, including Columbia University College of Dental Medicine , have highlighted how this bacterium can not only proliferate in the presence of tumor tissue, but also actively contribute to its growth.
The role of Fusobacterium nucleatum in colon cancer
Scientific attention to Fusobacterium nucleatum stems from the fact that this bacterium, normally part of the oral microbiota, is capable of migrating through the bloodstream and colonizing extraoral tissues, particularly those of the intestine. Research published in EMBO Reports has demonstrated that the microorganism uses an adhesive protein, called FadA (Fusobacterium adhesin A) , to bind to epithelial cells and colon cancer cells.
This link is not accidental: cancer cells express a protein called Annexin A1 , which facilitates bacterial adhesion. In effect, this creates a pathogenic cycle: the bacteria promote tumor growth, and the tumor facilitates the colonization of the bacteria. This mechanism not only amplifies cell proliferation, but may also make the tumor microenvironment more resistant to immune defenses.
Research suggests that Fusobacterium nucleatum can modulate inflammatory responses by interfering with cell signaling pathways and stimulating chronic pro-inflammatory processes. This explains why individuals with severe gum disease or untreated periodontal infections are at higher risk of developing gastrointestinal cancers than the general population.
Clinical evidence and prognostic factors
A study of 466 patients with colorectal cancer found that those with higher levels of Fusobacterium nucleatum and Annexin A1 tended to have a more rapid clinical course and a less favorable prognosis. These results suggested that expression of the molecule could be a prognostic biomarker , useful for assessing disease progression and response to treatment.
The clinical potential of this discovery is twofold: on the one hand, it allows us to identify at-risk patients through microbiological and molecular tests, on the other, it opens the way to new therapeutic strategies, for example, aimed at reducing the interaction between bacteria and tumor cells.
The concept of oral biomarkers as systemic indicators is one of the most innovative approaches in precision medicine. Detecting alterations in the oral microbiome—the set of microorganisms that populate the mouth—could, in the future, become an integral part of personalized cancer screening.
Periodontal diseases and systemic risk
Periodontology experts have long recognized that periodontal disease is not limited to a local condition. Chronic gum inflammation can promote bacterial dissemination and the release of inflammatory mediators into the bloodstream, contributing to cardiovascular, metabolic, and oncological disorders.
The bacterium Fusobacterium nucleatum , formerly known as part of the so-called "orange complex" identified in the Socransky classification, is implicated in numerous oral infections and tissue destruction affecting the periodontium. When it reaches other parts of the body, its ability to adhere to and penetrate tissues makes it a potential cofactor in the development of neoplasms.
Professor Cristiano Tomasi , a lecturer at the University of Gothenburg and an active member of the Italian Society of Periodontology and Implantology (SIdP) , emphasized that the discovery of a direct correlation between the presence of the bacterium and the progression of colon cancer opens crucial research avenues. According to Tomasi, "the early identification of bacteria associated with certain systemic conditions will allow us to integrate dental diagnosis into preventive medicine."
From the mouth to the'intestine: the microbiome as a connected system
The human body is home to over 100 trillion microorganisms that make up the microbiome , a dynamic ecosystem that influences digestion, immunity, and even metabolism. When the balance of this system is disrupted—a condition known as dysbiosis —pathological mechanisms can arise that can impact the entire organism.
In the case of the oral microbiome, poor hygiene, excessive antibiotic use, oxidative stress, and a low-fiber diet can alter the bacterial flora, allowing the proliferation of opportunistic species such as Fusobacterium nucleatum . Once introduced into the systemic circulation, these species can reach the intestine and interfere with the epithelial barrier, promoting chronic inflammation and the formation of tumor-promoting microenvironments.
According to an analysis published in Quotidiano Sanità, 38% of Italians suffer from untreated gum disease, and approximately 19% have advanced periodontitis. This population is at higher risk of systemic diseases, including gastrointestinal cancers, compared to those who maintain regular hygiene and dental checkups.
Fusobacterium nucleatum and peri-implantitis: a new correlation hypothesis
Recent research has highlighted the presence of Fusobacterium nucleatum also in samples taken from patients suffering from peri-implantitis , suggesting that the bacterium may also play a role in inflammatory processes linked to dental implants.
This discovery reinforces the idea that oral microorganisms may act as mediators between local health and systemic disease. Peri-implantitis, which already causes bone loss around the implant and the risk of rehabilitation failure, could constitute an additional entry point for pathogenic bacteria into the circulatory system.
The overlap between oral pathogenic microbes and systemic disorders is currently the subject of interdisciplinary studies involving dentists, gastroenterologists, and molecular microbiologists. Tracing bacterial species common to both the oral and intestinal regions is providing increasingly robust evidence of a clinically important "mouth-gut" axis.
Prevention and oral hygiene as a systemic strategy
The idea that proper oral hygiene can have protective effects even on distant organs is no longer just a theory. Experts recommend regular visits to the dentist, especially for those with a family history of cancer, chronic diseases, or a predisposition to inflammation.
Integrated prevention programs are emerging in several countries, aiming to include dental checkups in screening protocols for systemic diseases. In Italy, however, data reveal that nearly 60% of the population forgoes regular dental care for financial reasons. This forgoing, according to estimates, can result in an exponential increase in the risk of inflammatory complications and chronic infections.
Oral health education should therefore be considered an integral part of cancer prevention. Avoiding plaque buildup, maintaining a balanced diet, reducing sugar and tobacco consumption, and undergoing professional hygiene checks can significantly reduce the proliferation of opportunistic bacteria.
For professional information and updates in the dental field, you can consult the portals dedicated to dentists and oral health practices based on scientific evidence.
Towards a new precision oral medicine
Studies on the relationship between the oral microbiome and colon cancer are part of a broader vision of precision medicine, which aims to identify individual risk factors based on the patient's genetic and microbial profile.
In the near future, diagnostic tests based on saliva or plaque samples could become complementary screening tools for colorectal cancer prevention. At the same time, therapeutic approaches aimed at modulating the microbiome through probiotics, prebiotics, and personalized therapies are being explored.
The goal is not only to identify new treatments, but above all to understand how the microbial environment interacts with the body in a complex and bidirectional way. The implications of these studies could extend beyond oncology, involving cardiology, endocrinology, and neuroscience.
The connection between oral health and systemic health is now a cornerstone of contemporary biomedical research. The awareness that a simple imbalance in oral flora can influence the development of serious diseases such as colon cancer marks a radical transformation in the way we think about prevention.
Continuing to investigate these connections means promoting a more integrated medicine, in which oral care becomes part of a comprehensive approach to individual health.
