August 30, 2009
Diarrheal bacterial linked to colon cancer
U.S. researchers, in studies involving mice, link a diarrhea-causing bacteria to a type of colon cancer.
Study leader Dr. Cynthia Sears of The John Hopkins University School of Medicine says strains of this common bacteria -- Bacteroides fragilis -- sometimes trick immune system cells into allowing colon tissue to be continuously inflamed and may set the stage for malignancy.
This could be the H. pylori of colon cancer,Sears says in a statement.
H.pylori is a bacteria known to cause stomach ulcers and is suspected of causing the majority of stomach cancers, she said. The studies in mice suggest Bacteroides fragilis may use tissue inflammation to cause colon cancer in a similar way that H. pylori causes stomach tumors, the study says.
Sears says enterotoxigenic bacterium -- germs widely known to cause diarrhea in children and adults -- have been linked in a previous study in Turkey to 40 percent of colon cancers. These bacteria can colonize in the gut causing no symptoms in some people, while diarrhea and colon inflammation linked to cancer growth develops in other people.
The findings are published in the journal Nature Medicine.