Moderate exercise may improve gut health, survival of patients with colorectal cancer
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Moderate exercise may improve longevity for patients with colorectal cancer by acting on the gut microbiome, according to a study published in American Journal of Cancer Research.
This benefit may also extend to patients with cancer and obesity who generally have a less healthy microbiome, researchers wrote.
“There have been many studies on physical activity showing that it improves survival after colorectal cancer, and while we are still awaiting a formal clinical trial, that has been quite well-established,” Cornelia M. Ulrich, PhD, MS, executive director of the comprehensive cancer center at University of Utah's Huntsman Cancer Institute and Jon M. and Karen Huntsman presidential professor in cancer research, told Healio. “However, the molecular or biologic mechanisms underlying that association have not been conclusively identified. So, we have done quite a lot of work looking at inflammation, which is one part of promoting angiogenesis, and also now the gut microbiome.”
The findings are part of the ColoCare study, which includes more than 3,500 individuals with a new diagnosis of colon or rectal cancer. The study is being conducted at Huntsman and other leading cancer institutes, including Fred Hutchinson Cancer Center, Moffitt Cancer Center, University Hospital Heidelberg, Cedars-Sinai Medical Center, Washington University in St. Louis, and University of Tennessee.
Ulrich spoke with Healio about the mechanism through which exercise may benefit the gut microbiome and discussed future research into this topic.
Healio: What inspired you to conduct this study?
Ulrich: The goal of the ColoCare study is to identify factors that impact health of patients with colorectal cancer after a diagnosis. There are many factors that can play a role — some are health behaviors, some are biologic and some are treatment-related. We are trying to take a comprehensive approach to understanding the interface of all these factors.
A second reason we wanted to do the study was to understand the interface between body mass index or obesity and physical activity. Often, we see people who are obese but seem to be metabolically healthier than other people with the same BMI. So, a desire to understand whether physical activity has an influence independent of body weight was another part of what motivated us to conduct this study.
Healio: What are the three analyses within the ColoCare study?
Ulrich: We have been building an evidence base around these mechanisms and how they impact survival, recurrence and wellbeing after diagnosis. We looked at inflammatory biomarkers and biomarkers of angiogenesis in patients with colorectal cancer before surgery. We’ve shown in previous studies that these biomarkers predict higher levels of systemic inflammation and promote worse survival.
The second analysis is of BMI and physical activity to understand how physical activity impacts systemic inflammation in our patients with colorectal cancer. We categorized patients into four combinations of physical activity levels/BMI. That is where we observed that obesity is the key driver of systemic inflammation in the body.
The third analysis is of how the gut microbiome relates to BMI and physical activity together and independently. That analysis was especially novel because it is the first one to be done on the microbiome in patients with colorectal cancer that looked at physical activity. There have been smaller studies comparing athletes vs. nonathletes, but nothing in patients with colorectal cancer. What’s interesting is that physical activity seems to be the main driver of gut health more than obesity.
We knew from preclinical studies that obesity is a driver of greater gut dysbiosis, but we added this component of physical activity to understand whether that would offset the effects of obesity on the gut microbiome.
Healio: What did you find?
Ulrich: We found that, indeed, patients categorized as inactive had much lower alpha diversity in their gut microbiome than active patients. Higher diversity of the microbiota in the gut has been associated with survival. This finding was independent of BMI status. Although the gut microbiome of patients categorized as normal weight was more diverse than that of patients classified as overweight/obese, physical activity nevertheless did provide some benefit to those in the overweight/obese group. We see that obesity can reduce alpha diversity in the microbiome, but individuals with obesity can still offset that to some extent through physical activity. This study was not an intervention study and I think that should be the next step.
This study shows health behaviors are truly important in driving outcomes. Often, they are not valued as much because there is not a big industry supporting them. However, this is so important for patients, because they want to know what they can do for themselves to improve their health and chances of survival.
Healio: What is currently recommended as far as exercise for patients with cancer?
Ulrich: ASCO has come out with clinical recommendations and guidelines for physical activity. Even during treatment, exercise and resistance training can reduce levels of chronic fatigue and help improve quality of life, as well as physical function.
It is also important to understand that you cannot produce a clear prescription that says, “You need to do this for this many days a week and you’ll have this effect,” because each patient starts at a different level, especially depending on their treatment. So, we need to precision tailor exercise, as we do at Huntsman Cancer Institute. We have a number of programs where our kinesiologists work with our physical therapists to evaluate people’s level of performance continuously during treatment and then build a program for them that they can implement.
For more information:
Cornelia M. Ulrich, PhD, MS, can be reached at Huntsman Cancer Institute, 2000 Circle of Hope Drive, Salt Lake City, UT 84112; email: neli.ulrich@hci.utah.edu.
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