Changes in Abundance of Oral Microbiota Associated with Oral Cancer

TLDR

Individual bacteria and shifts in the microbiome have been associated with human diseases including cancer. The study aimed to investigate microbiome changes associated with oral cancers by profiling tumor and matched normal tissues. This was done by sequencing 16S rDNA hypervariable region amplicons from the samples. In both discovery and confirmation cohorts, Firmicutes (especially Streptococcus) and Actinobacteria (especially Rothia) were significantly depleted in cancer tissues compared to matched normal, with similar reductions seen in pre‑cancers but not in healthy contralateral sites; weighted UniFrac analysis of 12 taxa separated most cancers, especially node‑positive cases, suggesting the oral microbiome could be used to monitor oral cancer development, progression, and recurrence.

Abstract

Individual bacteria and shifts in the composition of the microbiome have been associated with human diseases including cancer. To investigate changes in the microbiome associated with oral cancers, we profiled cancers and anatomically matched contralateral normal tissue from the same patient by sequencing 16S rDNA hypervariable region amplicons. In cancer samples from both a discovery and a subsequent confirmation cohort, abundance of Firmicutes (especially Streptococcus) and Actinobacteria (especially Rothia) was significantly decreased relative to contralateral normal samples from the same patient. Significant decreases in abundance of these phyla were observed for pre-cancers, but not when comparing samples from contralateral sites (tongue and floor of mouth) from healthy individuals. Weighted UniFrac principal coordinates analysis based on 12 taxa separated most cancers from other samples with greatest separation of node positive cases. These studies begin to develop a framework for exploiting the oral microbiome for monitoring oral cancer development, progression and recurrence.