FCRC Beyond Blue Fall 2021 - Flipbook - Page 10
HOTTopic
The
Feature STORY
MICROBIOME
With the rise of pop culture’s interest in gut health, the microbiome has taken center stage. Simply
put, the microbiome refers to all bacterial cells living inside the gastrointestinal tract. When the gut
microbiome is out of whack, there is an imbalance of good bacteria versus bad bacteria. This imbalance
can be caused by a variety of factors like diet, medicines, stress, and disease, among others. Many
scientists around the world are avidly studying the microbiome to uncover health insights.
We connected with Drs. Michael G. White and Nadim Ajami
from The University of Texas MD Anderson Cancer Center to
help us understand the role of the gut microbiome, and more
specifically, its role in colorectal cancer.
Microbiome Defined
The gut microbiome is a complex
environment of bacteria, viruses, and fungi
comprising the vast majority of genetic
diversity within each person—well beyond
an individual’s own DNA. Increasingly
well-defined, the gut microbiome has been
linked with a myriad health conditions.
These interactions are now understood
to occur both locally (in the gut) and
systemically (with impact throughout the
body) through changes in the immune
system among other mechanisms. The
gut microbiome’s local proximity to the
colon led many early investigators to study
its impact on colorectal cancers (CRC),
placing CRC at the forefront of studies
in the microbiome’s influence on cancer
development, progression, and response
to therapy.
Connection to CRC
While CRC incidence and mortality have
decreased over recent years, its increase
in young adults has prompted a deeper
examination of factors affecting the
gut microbiome, such as environmental
exposures and diet. A variety of studies
have demonstrated an imbalance in the
microbiome of CRC patients, including a
disproportionate amount of bacteria linked
to pro-tumor microenvironments, DNA
damage, and modulation of short chain
fatty acids within the gut that may act as
protective agents for cancers. CRCs also
demonstrate an increased diversity of
viruses in their microbiome. Whether this
is connected to the imbalance of gut
bacteria in cancer patients or they are
related to cancer development is an area
of active investigation.
Future of CRC Care
Recent findings have the potential to
benefit CRC patients and the general
population in the near future. Specific
microbial species, metabolites, and
alterations are being investigated
and validated as strategies for cancer
interception, treatment, and prevention.
Carefully controlled trials to regulate the
microbiome via fecal transplantation
are underway to measure the impact of
shifting the composition and structure
of the gut microbiome. Early data from
melanoma patients demonstrates that
fecal transplantation can induce a response
to immunotherapy in patients who initially
were resistant.
Microbial markers of disease progression
(genetic material of bacteria and viruses,
other proteins, or metabolites) may also
improve surveillance and treatment
strategies. A future microbial signature
could potentially act as a marker for risk
of developing metastatic CRC, measured
using a simple blood draw. This could
help doctors decide when to prescribe
adjuvant chemotherapy and influence the
development of future therapeutics.
Lastly, microbial markers of CRC hold
promise for fine-tuning cancer screening
guidelines for the general public. Given
the rising rates of CRC in young adults,
the percent of the population for whom
screening is recommended continues to
increase. However, due to a limited number
of endoscopists in the U.S., risk assessment
tools need improvement. Gut microbial
insights could generate more effective
screening methods, while also making
sure those at the highest risk receive the
screening they need.
BU RN I NG
UESTIONS
Practical Takeaways
Microbiome profiling is not akin to glucose
or blood pressure measurements, where
a single number defining “healthy” can
be applied to the general population.
Moreover, its complex interactions
affect a variety of health conditions in
different ways—therefore, an “ideal” gut
microbiome for any given condition is not
fully defined. Your microbiome should
only be studied under the direction and
guidance of your medical team.
Food. We can’t live without it, but for many in the
colorectal cancer community, it’s hard to live with it. Yet
as doctors, nutritionists, and research data all say: Diet
and nutrition play an essential role in cancer prevention
and treatment. Food is a topic we can’t ignore.
EASIER SAID THAN DONE.
Direct-to-consumer
profiling services (kits
you can buy from online
and box stores) do not
offer appropriate medical
follow-up and guidance.
To ensure your microbiome is functioning
in the healthiest capacity, the best advice
to date is the simplest: follow a diverse,
high-fiber diet (as medically able),
avoid probiotic supplements (unless
recommended by your physician), and only
make changes after directed discussion
with your physician.
Authors
Michael G. White
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Nadim Ajami
Michael G. White, MD, Department of Surgical Oncology, The University of Texas MD Anderson
Cancer Center, Houston, Texas, USA, and Program for Innovative Microbiome and Translational
Research (PRIME-TR), The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
Nadim Ajami, PhD, Program for Innovative Microbiome and Translational Research (PRIME-TR),
The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
View this article online to see the authors’ references.
FightColorectalCancer.org/blog/the-gut-microbiome
Join the Fight at FIGHTCRC.ORG
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