Oral microbiota: a barrier against cancer?

Smoking and poor oral hygiene are two major risk factors of mouth or throat cancer associated to a decrease in the diversity of the oral microbiota. What differences are there between the latter and the oral microbiota of a non-smoker and hygiene-conscious individual?

 

To answer this question, a German and American research team analyzed the composition, diversity and functions of the oral cavity microorganisms of 121 patients with oropharyngeal carcinoma and 242 healthy individuals.

Risk of decreased diversity in the microbiota

The major risk factors in the development of oropharyngeal cancer (tobacco, alcohol, oral hygiene, papillomavirus infection) were analyzed for all 363 volunteers. The microbial composition of the oral cavity was then detailed for each individual in order to identify the main differences between the two populations. As a result, researchers found out that although not all cancer risk factors are associated with significant changes in the microbiota, smoking and poor dental health seem to be the source of a clear deterioration of the oral ecosystem. This deterioration is associated with a decrease in microbial diversity and disturbance of certain essential microbiota functions (glucose metabolism, transport of metals and organic compounds...).

Tooth loss: a confirmed risk

The study mainly allowed to underline the major impact of the total loss of teeth. The disappearance of a privileged “habitat” for microorganisms drastically decreases the microbial diversity and the functions associated to the preservation of a healthy mouth. The lack of teeth is directly associated to the onset of oropharyngeal cancer and could also increase the risk of cancer by modifying the local microbiota. Although at this time it is a mere hypothesis, the study results at least confirm that the presence of some risk factors in the development of oropharyngeal cancer does change the composition and functions of the oral microbiota.

 

Sources:

Daniela Börnigen, Boyu Ren, Robert Pickard et al. : Alterations in oral bacterial communities are associated with risk factors for oral and oropharyngeal cancer, Nature, Scientific reports | 7: 17686 | DOI:10.1038/s41598-017-17795-z.