Some Gut Bacteria Linked to Precancerous Colon Polyps

New study looks at microbiome’s influence, findings may help with prevention

Illustration of a polyp inside of a colon with a laparoscopic light near it
Image: SciePro/iStock/Getty Images Plus

A new study by Harvard Medical School investigators at Massachusetts General Hospital has linked certain types of gut bacteria to the development of precancerous colon polyps. Their results are published in Cell Host & Microbe.

“Researchers have done a lot of work to understand the relationship between the gut microbiome and cancer. But this new study is about understanding the microbiome’s influence on precancerous polyps,” said co-corresponding author Daniel C. Chung, HMS professor of medicine, medical co-director of the Center for Cancer Risk Assessment at Mass General Cancer Center, and a faculty member of the gastroenterology division at Mass General.

Get more HMS news here

“Through the microbiome, we potentially have an opportunity to intervene and prevent colorectal cancer from forming,” he said.

Colorectal cancer is the second-leading cause of cancer-related deaths in the U.S., and rates of colorectal cancer are rising among young adults.

Nearly all colorectal cancers arise from a precancerous polyp. One of the best ways to reduce the incidence of colorectal cancer is to stop the growth at the polyp stage.

There’s more than one way for a polyp to develop. The two main types of polyps are tubular adenomas and sessile serrated polyps.

Risk factors for colorectal cancer and polyps include lifestyle factors like being overweight or obese, low physical activity levels, a diet high in red and processed meats, smoking, and alcohol use.

These factors also influence the bacteria that live in our intestines, collectively known as the gut microbiome.

Environmental factors and polyp growth

Researchers think these environmental influences could promote polyp growth in one of two ways. Either they change the gut microbiome directly in a way that encourages polyp growth, or they promote polyp growth, which in turn influences the gut microbiome by directly affecting the cells lining the intestines.

Earlier, smaller studies trying to link the gut microbiome to polyps have not found a consistent pattern, though they didn’t look at these two types of polyps specifically.

To study the gut microbiome’s link to colon polyps, the researchers took data from 1,200 people getting routine screening colonoscopies.