When bacteria from your mouth enter your lungs, it's linked to advanced-stage lung cancer and tumor progression, a finding that raises serious questions about the long-term use of face masks, which could potentially accelerate this process. A retired pathologist also called for research into face masks' effects on nasopharyngeal and oropharyngeal bacterial flora
It's long been assumed that your lungs are a sterile environment, but it's recently been discovered that microbes from your mouth frequently enter your lungs. This alteration in your lung microbiome has now been linked to advanced-stage lung cancer,[i] raising questions about long-term mask usage and the risk of chronic diseases like cancer.
The team of researchers, from New York University (NYU) Grossman School of Medicine, revealed that when lungs were "enriched" with oral commensals, or microorganisms from your mouth, advanced-stage lung cancer was more likely, and it was linked with worse prognosis and tumor progression as well.[ii] The use of masks -- also known to colonize bacteria -- could accelerate the inhalation of oral microbes into your lungs, potentially affecting cancer risk.
Oral Microbes in the Lungs Linked With Advanced Lung Cancer
After analyzing the lung microbiomes of 83 adults with lung cancer, those with advanced-stage cancer had more oral microbes in their lungs compared to those with early-stage cancer, and oral commensals were also linked with decreased survival.
Specifically, Veillonella, Prevotella and Streptococcus bacteria -- all part of a normal oral microbiome -- in the lungs was associated with poor prognosis while Veillonella, Prevotella, Streptococcus and Rothia bacteria were linked with tumor progression.
The team previously found that oral commensals in the lungs are associated with increased inflammation in the lungs of healthy individuals and altered immune response, including the recruitment of cytokine interleukin-17 (IL-17), which plays a role in lung cancer.
"Given the known impact of IL-17 and inflammation on lung cancer, we were interested in determining if the enrichment of oral commensals in the lungs could drive an IL-17–type inflammation and influence lung cancer progression and prognosis," study author Dr. Leopoldo Segal said in a news release.[iii]
It turned out that Veillonella, which was enriched in those with advanced-stage disease, was not only linked to the expression of IL-17 but also to the TNF, PI3K-AKT and JAK-STAT signaling pathways. Veillonella are among the most abundant bacteria found in the mouth, as well as in saliva and dental plaque.[iv]
When one strain -- Veillonella parvula -- was introduced into the lungs of mice with lung cancer, they had decreased survival, weight loss and worsened tumors, a response that was associated with the increased expression of inflammatory proteins like IL-17.[v] "The data presented here suggest that lower airway dysbiosis induced by microaspiration of oral commensals affects lung tumorigenesis by promoting an IL17-driven inflammatory phenotype," the researchers noted.[vi]
They added that the microbiota in your lungs are "mostly affected by aspiration of oral secretions," and in turn are "in constant interaction" with your immune system.[vii] How does wearing a face mask affect this relationship?
Inhaling Bacteria From Your Mask Could Be Dangerous
While the featured study didn't expand into how the long-term usage of face masks could potentially enhance the amount of oral commensals that enter your lungs, possibly affecting lung cancer risk, James Morris, a retired consultant pathologist with University Hospitals of Morecambe Bay NHS Foundation Trust in England, raised a similar concern in April 2020.
In a BMJ rapid response, he stated that more research is needed on face masks' effect on nasopharyngeal and oropharyngeal bacterial flora.[viii] Morris has performed thousands of post-mortem examinations on people who died following viral respiratory tract infections, which he says were rarely the sole cause of death.
"In most cases there is a secondary contribution to inflammation from nasopharyngeal and oropharyngeal bacterial pathogens," he wrote, adding:[ix]
"If the public are advised to wear face masks, we must be certain that this will not adversely affect the bacterial flora of the upper respiratory tract. I am not aware of research in adults relevant to this question but there is quite extensive evidence from another field of study in which viral infection interacts with bacterial pathogens to cause sudden death.[x]"
He refers to research into sudden infant death syndrome (SIDS), which found that one factor involved was infants sleeping in the prone position and re-breathing bacteria growing in the mattress. "Moist mucus secretions from the upper airways soaked within the material of the mattress are an effective culture medium for bacterial pathogens," he said, which is "directly relevant to the question of home-made cloth face masks."[xi]
Morris didn't mention a cancer link, but he did make it clear that breathing in bacteria growing on your face mask could have serious health consequences:[xii]
"There is a potential for bacterial pathogens to grow in moist mucus soaked within the material, this could adversely alter the upper respiratory tract flora. Inhalation of bacteria and viruses directly into the lung in patients incubating Covid 19 could then risk synergistic interaction and a rapid deterioration in the patient's condition."
Morris recommended that, if you're going to wear a face mask, you should be sure to optimize your microbial flora by consuming naturally fermented foods. However, by wearing a face mask you're still going to be re-breathing bacteria and other pathogens and, likely, concentrating the amount of oral commensals that enter your lungs, with potentially devastating consequences.
Additional Research Challenging the Narrative that Masks are Safe and Effective
Learn more about the scientific research which calls into question the safety and effectiveness of masks on our database dedicated to curating research on the topic here: Face Masks (Lack of Safety and Ineffectiveness Research)
[i] Cancer Discov. 2021 Feb;11(2):293-307. doi: 10.1158/2159-8290.CD-20-0263. Epub 2020 Nov 11. https://cancerdiscovery.aacrjournals.org/content/11/2/293.long
[ii] The ASCO Post December 10, 2020 https://ascopost.com/issues/december-10-2020/the-lung-microbiome-may-affect-lung-cancer-pathogenesis-and-prognosis/
[iii] The ASCO Post December 10, 2020 https://ascopost.com/issues/december-10-2020/the-lung-microbiome-may-affect-lung-cancer-pathogenesis-and-prognosis/
[iv] Front. Cell. Infect. Microbiol., 20 April 2017 https://www.frontiersin.org/articles/10.3389/fcimb.2017.00139/full
[v] The ASCO Post December 10, 2020 https://ascopost.com/issues/december-10-2020/the-lung-microbiome-may-affect-lung-cancer-pathogenesis-and-prognosis/
[vi] Cancer Discov. 2021 Feb;11(2):293-307. doi: 10.1158/2159-8290.CD-20-0263. Epub 2020 Nov 11. https://cancerdiscovery.aacrjournals.org/content/11/2/293.long
[vii] Cancer Discov. 2021 Feb;11(2):293-307. doi: 10.1158/2159-8290.CD-20-0263. Epub 2020 Nov 11. https://cancerdiscovery.aacrjournals.org/content/11/2/293.long