Gut Microbiome Analysis May Provide an Effective Screening Tool for Colorectal Cancer

Key Points

  • Analysis of the gut microbiome in patients with different stages of colorectal cancer progression has found both an enrichment and depletion of several bacterial populations associated with adenomas and carcinomas.
  • Compared with clinical risk factors and fecal occult blood testing, gut microbiome analysis was more successful at significantly distinguishing healthy individuals from those with precancerous adenomatous polyps or invasive colorectal cancer.
  • Gut microbiome analysis has the potential to be an effective screening tool for colorectal cancer.

An analysis of the gut microbiome in patients from three clinical groups representing the multistage progression in colorectal cancer has found that the composition of the gut microbiome differentiates individuals with healthy colons from those with adenomas and carcinomas. Adding gut microbiome analysis to other fecal tests may provide an improved, noninvasive tool for colorectal cancer screening. The study by Zackular et al is published in Cancer Prevention Research.

Study Methodology and Results

Researchers analyzed stool samples from 90 subjects: 30 healthy individuals, 30 patients with precancerous adenomatous polyps, and 30 patients with invasive colorectal cancer. The researchers used logit regression models to differentiate between patients in the healthy and adenoma clinical groups. Preliminary models were generated using age, gender, race/ethnicity, body mass index (BMI), and medication use as independent variables.

Using this information, the researchers identified gut microbiome signatures for each group. Adding analysis of these signatures to assessment of age and race improved prediction of the presence of precancerous adenomatous polyps 4.5-fold. Adding analysis of the gut microbiome signatures to assessment of age, race, and BMI improved prediction of the presence of invasive colorectal cancer 5.4-fold.

In addition, analysis of the gut microbiome signatures was better than fecal occult blood testing in distinguishing individuals with precancerous adenomatous polyps from those with invasive colorectal cancer (area under the curve [AUC] = 0.617 and AUC = 0.952, respectively). Assessing BMI, fecal occult blood test results and gut microbiome signatures together further improved the ability to distinguish between the two conditions (AUC = 0.969).

“Our data show that gut microbiome analysis has the potential to be a new tool to noninvasively screen for colorectal cancer,” said Patrick D. Schloss, PhD, Associate Professor in the Department of Microbiology and Immunology at the University of Michigan Medical School in Ann Arbor and coauthor of the study, in a statement. “We don’t think that this would ever replace other colorectal cancer screening approaches. Rather we see it as complementary.” 

Dr. Schloss is the corresponding author for the Cancer Prevention Research article.

Funding for this study was provided by the National Institutes of Health. The researchers reported no conflicts of interest.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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