Gut Microbes May Play a Role in Bowel Cancer

Amy Taylor March 07, 2014

The microbes living in the gut could spur the development of intestinal tumours that lead to bowel cancer, a new study suggests.

Bowel cancer or colorectal cancer, results from a series of genetic changes that cause healthy cells to become progressively cancerous, first forming early tumours called ‘polyps’ that can eventually become malignant. Although these genetic changes or mutations can occur anywhere in the human intestine, certain types of colorectal cancer tend to develop in particular locations, suggesting that additional, non-genetic factors contribute to tumour growth and dictate where polyps appear.

A team of researchers from Icahn School of Medicine at Mount Sinai, New York examined whether gut microbes have a role in tumour development. In previous experiments, they noticed that mice carrying polyp-causing mutations develop polyps only in a limited section of the intestine, despite the mutations being present in all cells along the intestine.

Killing off certain gut bacteria may reduce risk of colorectal cancer

In the current study, they treated mice with antibiotics to disrupt the populations of microbes living in their gut. This treatment prevented the formation of polyps, showing that bacteria are essential for early tumour development in this model. The authors propose that bacteria cross from the gut into the tissue of the intestinal wall, triggering inflammation that promotes tumour growth.

While more research is needed, the new findings suggest it may be possible to reduce the risk of colorectal cancer in genetically susceptible individuals by removing certain types of gut bacteria. They may also help explain some of the non-genetic factors that have been implicated in colorectal cancer.

"In addition to genetic changes, various lifestyle-related factors, such as obesity and diet, have been linked to colorectal cancer. Some of these lifestyle factors appear to affect the types of bacteria present in the gut," explains Dr Lira. "Ultimately, understanding the interplay between genetic mutations, gut microbes, and inflammation may lead to novel diagnostics and therapies for intestinal cancer."

The study was published in the Journal of Experimental Medicine.