Lung tissue microbial profile in lung cancer is distinct from emphysema

The composition and structure of site-specific microbiota have been investigated as potential biomarkers for a variety of chronic inflammatory diseases and cancers. While many studies have focused on the changes in the airway microbiota using respiratory specimens from patients with various respiratory diseases, more research is needed to explore the microbial profiles within the distal lung parenchyma in smokers with lung cancer and/or emphysema.

To describe and contrast lung tissue-associated microbial signatures in smokers with lung cancer and/or emphysema, we employed culture-independent pyrosequencing of 16S rRNA gene hypervariable V4 region and compositional analysis in non-malignant lung tissue samples obtained from 40 heavy smokers, including 10 emphysema-only, 11 lung cancer-only, and 19 with both lung cancer and emphysema.

The emphysema-only group presented a lower bacterial community evenness defined by a significantly lower Shannon diversity index compared to the lung cancer patients with or without emphysema (P = 0.006). Furthermore, community compositions of lung cancer patients with or without emphysema were characterized by a significantly lower abundance of Proteobacteria (primary the genera Acinetobacter and Acidovorax) and higher prevalence of Firmicutes (Streptococcus) and Bacteroidetes (Prevotella), compared to emphysema-only patients. In conclusion, the lung microbial composition and communities structures of smokers with lung cancer are distinct from the emphysema-only patients. Although preliminary, our findings suggest that lung microbiome changes could be a biomarker of lung cancer that could eventually be used to help screening for the disease.