Gut bacteria might be an indicator of colon cancer risk

Date:
September 17, 2021
Source:
University of Washington School of Medicine/UW Medicine
Summary:
Researchers are finding a link between the increased presence of
certain bacteria in a gut biome and colon cancer.



FULL STORY ==========================================================================
A study published today in the journal Cell Host & Microbe reported that
the increased presence of certain bacteria in a gut biome indicates a
greater likelihood that colon polyps will become cancerous.


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In his research, William DePaolo, associate professor at the University
of Washington School of Medicine, tracked 40 patients who had undergone
routine colonoscopies and had biopsies taken near the polyps to identify bacteria present at relatively higher levels compared with those of
patients who were polyp-free. All the patients were between the ages 50
and 75, and 60% were women.

"The rising incidence of colorectal cancer is a major health concern, but little is known about the composition and role of microbiota associated
with precancerous polyps," the study states.

DePaolo's research team found that a common bacteria, non-enterotoxigenic Bacteroides fragilis, was elevated in the mucosal biopsies of patients
with polyps.

The research also found distinct microbial signatures distinguishing
patients with polyps from those without polyps, and established a
correlation between the amount ofB. fragilisin the samples and the
inflammation of small polyps.

Upon closer examination, DePaolo found that the B. fragilis from patients
with polyps differed in its ability to induce inflammation compared to
the B.

fragilisfrom polyp-free individuals.



==========================================================================
"The whole idea is that most people look at advanced colorectal cancer
and think of the microbiome, but it's hard to determine if the microbiome
has changed and when it changed," DePaolo said. "So we took an earlier
look at the disease and asked when might the microbiome may be pushing
a polyp toward cancer." Also, when people think of the microbiome and
its role in disease, they often think of compositional changes where a potentially dangerous bacteria takes over, he added.

"What our data suggests is that, in order to survive within an
environment where metabolic and inflammatory changes are occurring, a
normally healthy gut and related bacteria may adapt in such a way that
causes it to contribute to the inflammation rather than suppress it,"
DePaolo explained.

Only 5% of the polyps in the colon actually turn out to be cancerous,
he said.

He said polyps seem to develop in the same areas of the colon repeatedly
-- and he theorized that in fact new screenings for colon cancer could
look for key bacteria inhabiting the gut -- and the amounts of this
particular strain of B.

fragilis -- before pre-cancerous polyps even develop.

Colorectal cancer is the third leading cause of cancer in the United
States, and its incidence is rising among younger adults. If a screening
were available to test the microbes, before a polyp even appears, it
could be a key factor to drive these rates down, DePaulo suggested.

The next step, he said, is to expand the study to 200 patients to
determine whether a fecal sample might be used as a surrogate for the
mucosal biopsy.

This study was supported by UW startup funds; funds from the Rodger
C. Haggitt Endowed Chair Fund, R01CA220004, U01CA152756, it was also
supported by a Washington Research Foundation Distinguished Investigator
Award and by startup funds from the Institute for Systems Biology.

========================================================================== Story Source: Materials provided by University_of_Washington_School_of_Medicine/UW_Medicine.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Melissa C. Kordahi, Ian B. Stanaway, Marion Avril, Denise Chac,
Marie-
Pierre Blanc, Benjamin Ross, Christian Diener, Sumita Jain,
Paul McCleary, Ana Parker, Vincent Friedman, Jennifer Huang,
Wynn Burke, Sean M. Gibbons, Amy D. Willis, Richard P. Darveau,
William M. Grady, Cynthia W. Ko, R. William DePaolo. Genomic and
functional characterization of a mucosal symbiont involved in
early-stage colorectal cancer. Cell Host & Microbe, 2021; DOI:
10.1016/j.chom.2021.08.013 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/09/210917110850.htm

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