How Lung Cancer Is Linked To Microbes

Clker Free Vector Images/Pixabay

Some bacteria that inhabit the lungs cause cell damage, that in turn, leads to cancer.

By Patrick James Hibbert 

16 NOV 2019

Collectively, the microorganisms that live in and on the human body have a profound effect on human health. Cultivating microorganisms that inhabit the lungs is hard to do so the scientific community knew little about those microbes; if they even existed. 

New techniques were developed recently however that allowed the collection of evidence for and against previous theories, techniques like PCR (Polymerase Chain Reaction) that showed the RNA of bacteria present in the lungs. And in comparison to the upper airways, fewer bacteria resided in the lungs and lower respiratory systems. 

Predominant Phyla That Make Up The Lungs Microbiome:

• Bacterioidetes
• Firmicutes

Predominant Phyla That Make Up The Lower Respiratory System:

• Pseudomonas
• Streptococcus
• Fusobacterium
• Megasphaera
• Sphingomonas

Pathogenic microorganisms are capable of producing inflammation in the lungs. For example, microorganisms like Haemophilus, Influenzae, Enterobacter, E.Coli, Pneumococcus, Legionella, and Moraxella have all shown this ability. 

And since chronic inflammation is now accepted as an important carcinogenic factor, the role of bacteria in the development of lung cancer has attracted significant attention from researchers worldwide. 

A recent review of the connection between the lung’s microbiome and lung cancer was done by researchers in Moscow, Russia. Their aim was to organize the available data on lung cancer microbiome and its role in malignant tumor progression. They published their study in Hindawi and highlighted the topics of therapy resistance, cancer-causing bacteria, biomarkers, and tumors.

They brought to light that resistance to checkpoint inhibition cancer therapy might result from an abnormal composition of microbes in microbial communities. 

They highlight two studies that support this theory. One that showed the efficiency of this therapy decreasing dramatically upon antibiotic use. And another that showed disruptions in mice T-cell functioning after receiving oral antibiotic therapy, a disruption that appeared to increase their receptivity to artificially induced melanomas and lewis lung carcinoma.

Studies reveal that a significant shift in the lung’s microbial community may lead to lung cancer. Some bacteria can also be a telltale sign of lung cancer, in effect be a biomarker. 

All lung cancers have biomarkers even though no two types or subtypes are the same according to the American Lung Association. A biomarker is a substance in an organism that indicates a disease, infection, or environmental exposure. Studies suggest Veillonella and Megasphaera are lung cancer biomarkers.

Phyla Associated With Lung Cancer:

• Helicobacter pylori
• Bacteroides fragilis
• Capnocytophaga 
• Selenomonas
• Veillonella
• Megasphaera
• Neisseria
• Granulicatella adiacens‘
• Fusobacterium nucleatum

Helicobacter pylori induces cancer in the lungs, and Bacteroides fragilis toxin disrupts the DNA repair system, which could lead to carcinogenesis. Capnocytophaga, Selenomonas, Veillonella, Megasphaera, and Neisseria can all be labeled as potential lung cancer biomarkers. 

In fact, a high concentration of the later microorganisms correlates with both small-cell carcinoma and adenocarcinoma. Granulicatella adiacens‘ is involved in lung tumor development,  and Fusobacterium nucleatum is capable of inhibiting apoptosis in tumor cells. Researchers also say bacteriotoxins appear to play a significant role in tumor development. 

Scientists discovered a bacteria-mutation association. They say tumors with TP53 mutations, a mutation commonly found in ovarian cancer, tend to associate with unique microbial communities. Also, the latest studies connect the TP53 mutation to the presence of the Acidovorax genus in the microenvironment, a bacteria commonly found in smokers’ tissue samples.