Changes to the microbial composition of the gut can drastically alter the development of certain bowel tumors, according to a study published today (March 3) in The Journal of Experimental Medicine. Researchers from New York City’s Icahn School of Medicine at Mount Sinai worked with a mouse model that develops tumors called serrated polyps in the cecum, the part of the large intestine proximal to the colon. The polyps arise in part because the mice are genetically engineered, via a pair of transgenes, to overexpress the growth factor HB-EGF. But genetics, the researchers found, are not the whole story. Their work revealed that bacteria are also required for tumor development-the ceca of transgenic mice raised on an antibiotic cocktail did not form polyps.

‘We were able to show that tumor formation was dependent on the microbiota present in that particular area of the intestine,” said Sergio Lira, who led the study. ‘In the presence of antibiotics, or of a slightly different cecum microbiota, the tumors did not develop.”

‘This study adds to our knowledge of links between the gut microbiome and colon cancer, where causation is now established in several animal models and correlations are intriguing in humans (although causation in humans […]