Can non-smokers get lung cancer? Oral bacteria may be the driving force behind it! British research reveals

Recently, a study published in the British Medical Journal found that it may be related to the abundance and types of oral bacteria.

Studies have shown that the oral microbiomes of people with lung cancer and those without lung cancer are different. The richer the bacterial species, the lower the risk of lung cancer.

Moreover, among them, a higher abundance of Bacteroidetes and Spirochaetes was associated with a lower risk of lung cancer, while an abundance of Firmicutes was associated with an increased risk of lung cancer.

An accompanying commentary points out that oral bacteria may induce chronic inflammation, promote cell proliferation and DNA changes, activate cancer-related genes, and increase blood supply to tumors.

The review article also raises several questions, such as how stable is the human oral microbiome over time? If it changes over time, what drives this change? How does exposure to polluted environments such as polluted air affect the oral and lung microbiomes?

The commentators pointed out that it is still unclear whether oral microbes are the cause of the disease or a marker of disease or immune activity, but if it is the former, it is important to know whether the effects of oral microbes on lung microbes sow the seeds and act locally.

The study analyzed 74,941 participants in the Shanghai Women's Health Study and 61,480 participants in the Shanghai Men's Health Study. All of these participants were non-smokers and their health status was assessed every 2 to 3 years after enrollment. During the follow-up of about 7 years, 90 women and 24 men were diagnosed with lung cancer.

The researchers also included 114 age- and sex-matched non-smokers for analysis and comparison of mouthwash samples. The education level and family history of lung cancer in the matched subjects were similar to those of the subjects with lung cancer.

Source: Thorax: Type and abundance of mouth bacteria linked to lung cancer risk in non-smokers. BMJ. Dec 14, 2020.

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