Common Gut Bacterium Associated with Colorectal Cancer

HRB-funded research in the Centre for Systems Medicine could lead to a new biomarker for colorectal cancer.

New evidence that a common gut bacterium is involved in colorectal cancer has been published by researchers in the Centre for Systems Medicine, RCSI (first author is Dr Lorna Flanagan and study PI is Dr David Hughes). The manuscript* is currently available online in the European Journal of Clinical Microbiology & Infectious Diseases.

The HRB funded research found a significantly increased presence of a common microbe Fusobacterium nucleatum (Fn) in tissue and stool samples of patients with colorectal cancers and colorectal adenomas. Additionally Fn infection levels were related with adenoma progression from early to advanced stages and the transition from an adenoma to cancer, highlighting the potential of Fn detection as a possible indicator of colorectal cancers. The research further found that cancer patients with low bacterial levels had significantly longer survival times than patients with moderate and high levels of the bacterium.

The research suggests that screening for Fn levels may be used as a new colorectal cancer detection method or to further inform existing screening strategies. Efforts to combat Fn infection could be considered for colorectal cancer patients with high levels of the bacterium to improve the survival prospects for these patients. Fn levels may be used to classify adenomas that may have a higher risk of disease progression to colorectal cancers with implications for increasing follow-up and at the possible use of anti-microbial treatments. Potentially, any impact of Fn infection on adenoma development and progression to more serious stages will be considerable, because 95% of all colorectal cancers arise from adenomas, but only a small number of them become cancerous. Currently, there are no reliable predictive markers of whether an adenoma will advance to cancer.