Scientists may have identified an important new factor in determining colorectal cancer risk -- and it lies in the gut.

People with colorectal cancer may have fewer "good" bacteria and more harmful bacteria in their guts than people without the cancer, according to a small new study published in the Journal of the National Cancer Institute.

New York University researchers examined the intestinal flora from stool samples of 47 people with colorectal cancer and 94 healthy people, and found that people with colorectal cancer have more Fusobacteria and Porphyromanas bacteria -- linked with gut and mouth inflammation -- than the healthy people.

People with the cancer were also more likely to be depleted of the beneficial bacteria Clostridia and butyrate, than those without cancer. Some Clostridia family bacteria ferment dietary fiber, while butyrate could play a role in inhibition of inflammation of the colon.

"Our next step is to study how diet and lifestyle factors modulate these gut bacteria associated with colorectal cancer. This may lead to ways to prevent this disease" Jiyoung Ahn, PhD, an assistant professor of population health at NYU Langone Medical Center and a member of NYU Cancer Institute, said in a statement.

It should be noted that researchers found an association, and not evidence that these differences in gut bacteria cause colorectal cancer.

In an accompanying editorial, Volker Mai and J. Glenn Morris Jr from the University of Florida noted that the new findings are exciting because they "may provide insights into future ways to reduce the risk of CRC [colorectal cancer]." However, they wrote, "given the complexity of these biologic systems, caution must be exercised (and a lot more research done) before proceeding too far in promoting changes in microbiota as a prevention strategy for CRC."

In addition, a host of other risk factors for colorectal cancer exist -- such as genetics, nutrition, obesity and exercise -- and therefore, it may be hard to tease apart cause and effect.