Bowel cancer, the second most common cause of cancer deaths in Britain, may be caused by an infection, researchers claim.

For the first time scientists have found a bacterium in colon cancer tissue which is not normally present in the gut. Two independent research teams have identified a potential link between the micro-organism, Fusobacterium, and the cancer.

If the link proves to be causal it opens up the prospect that bowel cancer might be treated, or prevented, with antibiotics. Stomach cancer has already been linked to infection with the micro-organism Helicobacter pylori, which causes inflammation and can be simply eliminated with drugs.

The researchers, led by Robert Holt of Simon Fraser University in Canada, claim other micro-organisms could cause inflammation elsewhere in the gut and could be a risk factor for bowel cancer. He said it was "especially surprising" to find Fusobacterium as it is a known cause of disease but is "a very rare constituent of the normal gut" and has not previously been linked with cancer. But it has been linked with ulcerative colitis, a bowel condition which is known to increase the risk of bowel cancer.

It is unclear whether Fusobacterium is a cause or a consequence of bowel cancer tumours. Even if it is a consequence, it could be useful as a biomarker of the disease.

The authors claim in the findings, published in Genome Research: "If Fusobacterium is found to be causative for disease, clinical trials could evaluate the effectiveness of antibiotics or vaccines to treat or prevent cancer."