The surest way scientists have to look for colon cancer is an invasive colonoscopy, a test which requires anesthesia and can leave people incapacitated for an entire day. However, a new study shows there may be an easier, effective way to screen for the cancer noninvasively. All you have to do is go with your gut feeling -- your bacteria, that is.

A new study published in Cancer Prevention Research, a journal published by the American Association for Cancer Research, shows that analyzing the bacteria in the colon was more successful at screening patients for precancerous adenomatous polyps and signs of colorectal cancer than fecal occult blood testing.

"A person's gut microbiome is the collection of all the bacteria in their gut," said Patrick D. Schloss, PhD, in a press release. Schloss is the associate professor in the Department of Microbiology and Immunology at the University of Michigan in Ann Arbor.

"The number of bacteria in the gut is huge; it outnumbers the number of cells in our bodies 10 to one, and the diversity of the bacteria present is critical to our health. By sequencing the V4 region of the 16S rRNA gene we were able to identify the bacteria present in each individual's gut microbiome."

In the study, 90 people contributed stool samples. The study consisted of 30 healthy people, 30 people who had precancerous polyps, and 30 people with colorectal cancer. The researchers found that each group had a different bacterial signature in their colons.

Using this knowledge, they were able to successfully screen people for precancerous adenomatous polyps, and for colorectal cancer, Schloss says. If these results are confirmed in a larger study, then testing for gut microbiome analysis in addition to fecal occult blood tests may be a less invasive way to test for colorectal cancer and warning signs.

The researchers were able to find unique microbiome signatures for each group. When they additionally factored in age and race, risk factors for colon cancer and precancerous polyps, they were able to increase prediction of precancerous adenomatous polyps by 4.5 times the amount of just the bacteria alone. When they additionally factored in BMI, another risk factor for colon cancer, they improved the accuracy of prediction by 5.4 times.

The study found that analyzing microbiome signatures in the gut together with fecal occult blood tests, age, race, and BMI was significantly better than analyzing for fecal occult blood tests alone.

"Our data show that gut microbiome analysis has the potential to be a new tool to noninvasively screen for colorectal cancer," said Schloss.

"We don't think that this would ever replace other colorectal cancer screening approaches, rather we see it as complementary."