A pair of studies published by Genome Research identified a potential link between a microorganism and colon cancer, after both sets of researchers found an abnormally large number of Fusobacterium cells in colorectal tumor samples.

In one project, a team led by Dr. Robert A. Holt of the BC Cancer Agency in Vancouver, British Columbia, Canada, and Simon Fraser University in Burnaby, British Columbia, verified an overabundance of the bacterium in colorectal carcinoma tissue compared with matched normal tissue specimens. As Holt noted in a statement highlighting the findings (available at http://genome.cshlp.org/content/early/2011/10/05/gr.126516.111.full.pdf+html) this discovery was particularly surprising because although Fusobacterium is a known pathogen, it is a very rare constituent of the normal gut microbiome and has never before been associated with cancer.

Whereas Holt’s group used RNA sequencing in their research, Matthew Meyerson, MD, PhD, of Dana-Farber Cancer Institute (Boston, Massachusetts) and the Broad Institute (Cambridge, Massachusetts), and colleagues used DNA sequencing. They, too, found Fusobacterium to be more prevalent in colorectal carcinoma tissue compared with normal colon tissue in 95 matched pairs.

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A confirmed connection between Fusobacterium and the onset of colorectal cancer would mark the first time any microorganism has been found to play a role in this type of cancer. Previous studies have suggested that Fusobacterium is associated with inflammatory bowel diseases such as ulcerative colitis, which can raise a person’s risk of developing colon cancer.

However, both investigative teams acknowledge that the precise role of this infection in colorectal carcinoma pathogenesis has yet to be determined; whether the infection is a cause or a consequence of these tumors is unclear. But if Fusobacterium is found to be a cause of the disease, clinical trials could evaluate the effectiveness of antibiotics or vaccines in the prevention or treatment of colorectal cancer.