Abstract
The emergence of a link between Helicobacter pylori infection and an increased risk of gastric cancer has raised an awareness of a possible link between colonic microbiota and colorectal cancer. Pertubation of the colonic epithelium by toxin-producing strains of Bacteroides fragilis may increase the risk of premalignant transdifferentiation. However, like H. pylori, B. fragilis exhibit an ability to modulate the normal host response to infection. We speculate this may be an underappreciated risk factor in the genesis of colon carcinogenesis in individuals colonised with toxin-producing strains of B. fragilis.