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Colon Cancer Linked to Bug
Recent years have brought a collection of studies linking certain diseases of the gastrointestinal system to bacteria, like gastric ulcers and ulcerative colitis. Now, two new studies link bacteria of the gut to colon cancer, which begs the question, could antibiotics one day be used to prevent cancer?
Colon cancer is the second most deadly form of cancer. It has certain known risk factors, like diet, inflammation, and conditions like ulcerative colitis and celiac disease. But bacteria have not been demonstrated to be one of them, until now.
Researchers in one study sequenced the RNA of colon cancer tissue and compared it to normal cells. They found that a microbe Fusobacterium was present much more frequently in the cancerous tissue than in the healthy cells. A second team carried out a similar experiment but studied the DNA of the cancerous and noncancerous tissue: they found that the same bacteria were present in the cancerous tissue.
Robert Holt, author of one of the studies, said that the results “were especially surprising because although Fusobacterium, the bacterium we found in colon tumors, is a known pathogen, it is a very rare constituent of the normal gut microbiome and has not been associated previously with cancer." The bacterium is also linked to another serious disease of the digestive system, ulcerative colitis, which is itself a risk factor for colon cancer. The interplay between the three variables – bacteria, autoimmune disease, and colon cancer – will need to be looked into further.
It’s important to point out that there is no indication of cause and effect in these studies. Both studies only found a correlation between the bacterium and colon cancer. More research will need to determine whether Fusobacterium is the cause or effect of colon cancer, or whether the relationship is more complicated than that. If Fusobacterium is shown to be a cause of colon cancer, it would open up the possibility of developing vaccines to prevent the disease, or antibiotics to target the bacterium.
Both studies were published in the October 18, 2011 online issue of Cancer Research.
October 25, 2011