Editor: Akhmetova Aigerim
Translator: Bolysbek Dana
Author: Bolysbek Dana
Around one in four cases of lung cancer occurs in non-smokers and known risk factors, such as second hand tobacco smoke, background radon exposure, air pollution, and family history of lung cancer don't fully explain these figures.
The type and volume of bacteria (microbiome) found in the mouth is associated with an increased risk of various cancers: esophageal, head and neck, and pancreas.
In this study, the scientists wanted to find out if this association could also apply to lung cancer, given that the mouth is the entry point for bacteria into the lungs.
The researchers drew on participants in the Shanghai Women's Health Study and the Shanghai Men's Health Study, who were lifelong non-smokers and whose health was monitored every 2-3 years after enrollment between 1996 and 2006. At enrollment, participants rinsed out their mouths to provide a profile of the resident bacteria.
Information was obtained on lifestyle, diet, medical history and other environmental factors that may affect the disease risk.
Experience has shown that a wider range of bacterial species was associated with a lower risk of developing lung cancer.A larger volume of Bacteroidetes and Spirochaetes species was associated with lower risk while a larger volume of Firmicutes species was associated with heightened risk. Specifically, within the Firmicutes species, a larger volume of organisms from the Lactobacillales order of microbes was associated with a heightened risk.
The study was observational, therefore, in the course of it, scientists could not establish the cause. David Christiani from Harvard University suggests that bacteria in the mouth can cause chronic inflammation, accelerate cell
proliferation and suppress the death of other cells, cause DNA changes and turn on cancer genes and their blood supply, which will help explain the findings.
He adds: “It remains unclear whether the oral microbiome, as measured in this and other studies, represents a causative agent or is only a marker of disease or immune activity. If this is the first, then it will be important to understand that the oral microbiome actually inoculates the lung microbiome and thus acts locally."
Source: https://medicalxpress.com/news/2020-12-abundance-mouth-bacteria-linked-l...
