It has been estimated that 20% of all cancers have microbes among the complex set of causes that contributes to their development.
Our microbiome – a community of bacteria, viruses and microorganisms populating parts of the human body, such as the skin, gut or mouth – has evolved along with the human race, and will no doubt continue to do so.
While a number of microorganisms are beneficial for our bodies, some microbes have been proven to be directly related to the formation of tumours – for example, the Helicobacter pylori – a bacteria which can cause stomach cancer – and the Papilloma virus, which can lead to cervical cancer. It has been estimated that 20% of all cancers have microbes among the complex set of causes that contributes to their development.
It is for this reason that investigating the relationship between microbes and cancer is becoming more and more important – both so as to understand whether certain viruses or bacteria can be the cause of certain types of cancer, and so as to set up better screening tests, thus improving prevention.
As a result of these investigations and for some years now, researchers have been more closely studying one particular peculiarity that has been observed: that some of the bacteria that are present in the oral microbiome of individuals with periodontitis, are also found in areas affected by colon cancer, pancreatic cancer and oral cancer.
A healthy mouth means a balanced body, and it is now time for oral health professionals to adopt a forward-thinking approach, rather than to merely focus on just mending teeth. Only through a healthy mouth can our bodies – as a whole – be healthy. Our goal in Curaden is to achieve a paradigm shift in the way the medical fraternity and health-interested public think. That’s the reason we bring you articles and studies showing new approaches and revealing fascinating connections between oral and overall health.
Ueli Breitschmid, CEO of Curaden
So far, it has not been scientifically proven that bacteria are a direct cause of these types of cancer, such as in the case of Helicobacter, for example. However, some kind of correlation is certain and understanding it could lead to a better evaluation of the risk factors, as well as an improved screening – by, for example, detecting a certain predisposition simply by taking a sample from the saliva.
Gum disease bacteria and cancer – what’s the connection?
People suffering from periodontitis host different bacteria in their mouths than healthy individuals do, but there is no unique microbe associated with this disease. Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Tannerella forsythia, Fusobacterium nucleatum, Prevotella intermedia, and Treponema denticola are all types of bacteria found in mouths suffering from periodontal disease. Some of them have also been found in cancers in the oral and gastrointestinal area.
Fusobacterium nucleatum and colon cancer
Fusobacterium is a microbe particularly present in dental plaque. It is also implicated in periodontal diseases. It has been intensely studied because it seems to affect the way our immune system responds to gum disease.
Normally Fusobacterium is associated with inflamed gums, but several studies – some of which are reviewed and collected here – have shown that it is also present in the gut microbiota of individuals with colon cancer. A research paper by the National University of Ireland describes how the networks that the bacteria build in the oral mucosa are very similar to those found in the colon tissue in cancer cases.
Scientists still do not know exactly how to explain this correlation: it is not clear whether these bacteria can migrate from the mouth to the intestine or if colon cancer promotes the development of Fusobacterium in the mouth. However, it is clear that there is a correlation – which is why researchers speculate that a simple mouth swab could be used to detect colon cancer more quickly.
Would you like to find out more about the connection between nutrition and microbiota? Watch the Curaden Academy webinar with Dr. Daniela Weiler, Leading Physician at the Department of Oncology, Cantonal Hospital of Lucerne.
Treponema denticola and pancreatic cancer
There is a correlation between another bacterium typical of chronic periodontitis – the Treponema denticola – and different types of cancer affecting the human digestive system: pancreatic cancer in particular.
Treponema denticola is a very invasive bacterium and together with other microbes is considered one of the most relevant and dangerous pathogens for gum disease. Surprisingly, several studies, including a research study by the School of Medicine at the New York University, have also confirmed its presence in pancreatic cancer samples.
Researchers at the University of Helsinki have described how the bacterium can negatively influence the regulation of the micro-habitat of the tissue in which the tumour develops. This is why researchers think that it could be among the co-responsible for the onset of pancreatic cancer – the fourth leading cause of death from cancer in the world.
Porphyromonas gingivalis, oral and pancreatic cancer
Porphyromonas gingivalis is among the most studied bacterium related to periodontitis. This microbe not only eludes the immune system, but it attacks macrophages – cells in the body specialised in detecting and destroying pathogens.
The bacterium is also linked to different types of tumours of the mouth, pancreas, lung, head and neck. In particular, findings presented at the American Association for Cancer Research’s Annual Meeting in 2016 and published in Gut Journal showed that patients with Porphyromonas gingivalis in their mouth experience a more than 50% increased risk of pancreatic cancer.
Porphyromonas gingivalis is now also accepted as a risk factor for oral cancer – in particular the oral squamous cell carcinoma, one of the most common malignancies of the oral cavity. However, the type of correlation between this bacterium and the cancer’s onset has not been fully defined by scientists.
This article is part of a series about microbiota and its connection to all aspects of the human body, including oral health. If you would like to learn more about this topic, have a look at other articles from the series:
- The oral microbiota in colorectal cancer is distinctive and predictive
- Treponema denticola chymotrypsin-like proteinase may contribute to orodigestive carcinogenesis through immunomodulation
- Oral microbiome and oral and gastrointestinal cancer risk
- Role of Fusobacterium nucleatum in Periodontal Health and Disease