It’s fairly common knowledge that a long-term diet of high-fat red meat and a sedentary lifestyle can be a dependable recipe for colon cancer.

But why? What is it about red meat or a high-fat diet that promotes cancer in the colon? And why is a lack of exercise such a risk?

Francis Giardiello and Cindy Sears are taking a look at the microbiome for answers.

“The bacteria in the colon may be influenced by what you eat,” Giardiello says, “and these environmental factors can give you certain populations of bacteria that, then, predispose you to colon cancer.”

But Giardiello, former director of the Johns Hopkins Division of Gastroenterology, isn’t looking at the bacteria that move through the colon; he’s looking at the bacteria stuck to the walls—the biofilm. Do the bacteria that adhere to the hollow organ play a role?

Working with Sears from the Johns Hopkins Division of Infectious Disease, Giardiello is exploring the relationship between biofilm and cancer.

The pair applied for an R1 grant from the National Institutes of Health for what would be the first-ever comprehensive study of its kind.

“We are going to evaluate many patients going through colonoscopy,” he says, “checking for these biofilms in their colon, and seeing if they associate with colon cancer or polyps.”

Giardiello says 141,000 Americans a year get colon cancer. And every year, 50,000 people die in the U.S. die of the disease. He estimates that 70 to 80 percent of colon cancer cases are the result of a poor diet and not enough physical exercise. While genetics and predisposition play a role, they’re far less important than the environment created by diet and a lack of exercise, says Giardiello.

Giardiello and Sears also plan to study the biofilm’s durability.

“Meaning, if you find it once in, say, January and then rescope the patient in July, are the biofilms still there? And are they the same? Are they durable?” he asks. “If that’s the case, this could be a biomarker for risk for colon cancer.”

Giardiello cites preliminary data from Sears indicating that the bacteria enterotoxigenic Bacteroides fragilis is particularly noxious to the lining of the colon.

“They’re causing inflammation,” he says. “And that inflammation can lead to cancer.”