Association of Fusobacterium in oral cavity and colorectal carcinomas

Objective:While particular imbalances in the gut microbiota have been linked to colorectal adenomas and cancers, some specific bacterium have been identified as a related factor. Recent studies have reported a high abundance of Fusobacterium in colorectal cancer(CRC) subjects compared to normal subjects. Fusobacterium is also known as a pathogenic species of oral microbiota, but it is not known if Fusobacterium plays a role in other part of the digestive tract. Fusobacterium may affect metabolic pathways for the carcinogenesis. We examined whether there is relationship between Fusobacterium in oral cavity and CRCs. Method:We assessed the abundance of Fusobacterium in CRCs, colorectal mucosa and saliva. We extracted DNA from mucosal biopsies and measured bacterial levels by quantitative PCR of the 16S ribosomal RNA gene. We also investigated the homology of Fusobacterium in oral cavity and CRCs.Result:In 41 CRC cases, Fusobacterium positivity was significantly higher in CRCs compared to controls(p<0.05). Fusobacterium was more detected in CRCs(12.9%) than in normal tissues(3.9%) respectively.The detection rate of Fusobacterium was 66.7% in saliva and CRC both-positive cases. Furthermore, we cultured a both-positive case, and showed homology.Conclusion:The results support a link between the abundance of Fusobacterium in oral cavity and CRC. Our data also indicate that there may be a route from the oral cavity to the CRC in Fusobacterium positive cases. We are now identifying DNA sequences, specific for the objective strains.