Researchers say they may have developed one more weapon in the battle against cancer, finding that gut bacteria can help identify people who have or are facing risks of getting colon cancer.
Early detection by analysis of gut bacteria, also termed gut microbiome, could lead to more successful treatment, they say.
The researchers used fecal samples to analyze the gut microbiome of 90 people; 30 healthy individuals, 30 having precancerous intestinal polyps, and a final 30 diagnosed with colon or rectal cancer.
The constituent bacteria of the gut microbiome of each group proved to be different, the researchers reported in Cancer Prevention Research.
"If our results are confirmed in larger groups of people, adding gut microbiome analysis to other fecal tests may provide an improved, noninvasive way to screen for colorectal cancer," says study author Patrick Schloss of the immunology and microbiology department at the University of Michigan.
When the gut microbiome analysis was added to other acknowledged risk factors associated with precancerous polyps -- race and age -- prediction of such polyps was increased 4.5-fold over standard fecal blood test, the researchers found.
When the analysis was combined with known risk factors associated with invasive colorectal cancer -- race and age plus body mass index -- predictions of the disease saw a five-fold improvement, they said.
The new testing technique takes advantage of the known fact that people with precancerous colon polyps or colon cancer will show a substantial drop in certain types of specific gut bacteria compared with healthy people, the researchers said.
Colorectal cancer deaths in the United States have declined steadily since 1975, thanks in great part to increased screening using both fecal blood tests and colonoscopies.
Still, more than 30 percent of U.S. adults are not given risk- and age-appropriate screening, the study authors say, and of those who do, most indicate a strong preference for noninvasive screening procedures.
Around 70 percent of colorectal cancers occur spontaneously without and clear origin cause, although alcohol, diet and chronic inflammation may be contributing factors, researchers say.
Changes in gut microbiome have previously been linked with obesity, inflammatory bowel disease and now, with colorectal cancer, suggesting analysis of gut bacteria should join the arsenal of cancer detection techniques, they say.
"Our data show that gut microbiome analysis has the potential to be a new tool to noninvasively screen for colorectal cancer," Schloss says. "We don't think that this would ever replace other colorectal cancer screening approaches, rather we see it as complementary."
