REGULAR EXERCISE POSITIVELY IMPACTS THE GUT MICROBIOME diversity in individuals with colorectal cancer. This study is the first to examine the relationship between physical activity and gut microbiome diversity in cancer patients.

Colorectal cancer begins in either the colon or the rectum. Depending on where they start, we refer to them as colon cancer or rectal cancer. Because they have many commonalities, we often group colon and rectal cancers together.

The exact cause of colorectal cancer for any individual is often unknown. However, lifestyle risk factors include sedentary behavior, a low-fiber diet low in fiber (and high in fat), and obesity. Alcohol and tobacco also increase colorectal cancer risk.

Other risk factors include inflammatory bowel diseases (for example, Crohn’s disease or ulcerative colitis), a personal or family history of colorectal cancer or polyps, and certain genetic syndromes. Inherited genetic syndromes include familial adenomatous polyposis (FAP) or hereditary non-polyposis colorectal cancer (Lynch syndrome).

Colorectal cancer statistics

Colon and rectal cancer are common in the United States, with over 150,000 cases annually. This incidence represents nearly eight percent of all cancers, making colorectal the third most common non-skin malignancy.

About four percent of men and women will be diagnosed with colorectal cancer at some point in their lifetime. Nearly 1.4 million people have a history of colorectal cancer in the USA.

In the USA, colorectal cancer is the third leading cause of cancer-related deaths in men and women and the second most common cause when we combine the numbers for men and women. Epidemiologists predict that the disease will cause approximately 52,580 deaths in 2022.

Fortunately, the death rate (the number of deaths per 100,000 people per year) from colorectal cancer has been dropping in both women and men for several decades.

However, while the overall death rate continues to drop, colorectal cancer deaths among people younger than 55 increased by one percent annually from 2008 to 2017.

Cancer Research U.K. reports that, in Great Britain, there are nearly 43,000 cases each year and nearly 17,000 deaths from colorectal cancer. Colorectal cancer is the fourth most common cancer in the United Kingdom, representing 11 percent of all new cancer cases.

Some good news: Researchers expect incidence rates for bowel cancer to fall by 11 percent in the U.K. between 2014 and 2035 to 74 cases per 100,000 people by 2035.

Cancer and the microbiome

Alterations in the microbes in our gut (the microbiome) associated with chronic inflammation are linked to breast, stomach, pancreas, liver, colon, and prostate cancers. I won’t spend a lot of time discussing the microbiome, as I recently published on it:

Here are some factors that impact the gut microbiota:

• Diet
• Age
• Antibiotic use

A new study examines the association between exercise and the gut microbiome in people with colon or rectal cancer. Let’s get right to the findings of this first-of-its-kind:

Regular physical activity is associated with higher levels of gut microbiome diversity, even among those who are overweight or obese.

The researchers obtained data from 179 individuals in the international ColoCare Study between October 2010 and March 2018. The ColoCare Study comprises recently diagnosed individuals with colorectal cancer (of any stage).

Subjects provided pre-surgery stool samples and body mass index (BMI) measurements. Scientists did gene sequencing on the stool samples to determine the subjects’ microbiome diversity.

The study subjects also filled out the International Physical Activity Questionnaire to document their activity level the year before a colorectal cancer diagnosis.

They characterized participants as sedentary if they had weekly activity levels below 8.75 MET. Having a metabolic equivalent of task of a minimum of 8.75 meets guidelines recommending at least 150 minutes weekly of moderate activity. This guideline may also apply to cancer survivors.

MET stands for the metabolic equivalent of task. One MET is the amount of energy used while sitting quietly. Physical activities may be rated using METs to indicate their intensity. For example, reading may use about 1.3 METs, while running may use 8 or 9 METs.

Results in detail

In summary, the gut microbiome of active and healthy-weight subjects appeared to be more diverse than that of inactive participants. Obese participants had lower alpha diversity than those with a healthy weight. Overall, there was a lower gut microbial diversity among inactive, obese, and overweight/obese/inactivity individuals.

A beneficial bacteria, Faecalibacterium, appeared enriched in active participants regardless of BMI.

Cancer and the microbiome — My take

The study reminds us of an association between weight, physical activity, and the microbiome. Because this study is cross-sectional, we cannot establish a causal relationship.

It would have been helpful to compare microbiota from healthy individuals. Finally, the subjects self-reported physical activity, which could have caused some misclassification of exercise levels.

I will continue to aim for a diet high in fruits and vegetables to support the diversity and health of my gut microbiome. I do not think we can overestimate the role of fiber in promoting good bowel health for most of us.

Other maneuvers that may improve our microbiome include getting adequate sleep, reducing stress, and getting regular physical activity. I also try to keep my processed food consumption down. Finally, appropriate colorectal screening is important. Don’t want the gold standard colonoscopy? There are many options available:

https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/colorectal-cancer-screening

https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/colorectal-cancer-screening

Thank you for joining me in this look at the microbiome and colorectal cancer.

The information I provided in this blog is for educational purposes only and does not substitute for professional medical advice. Please consult a medical professional or healthcare provider if you seek medical advice, diagnoses, or treatment. I am not liable for risks or issues associated with using or acting upon the information in this blog.