Marathon Running & Colon Cancer Risk: What You Need to Know
Marathon Runners, Take Note: New Study Links Extreme Endurance to Potential Colon Health Risks
Table of Contents
Thinking of pounding the pavement this weekend for a marathon? A recent study is making waves in the running community, suggesting a possible link between extreme endurance running and an increased risk of precancerous colon growths in younger adults.
The research, presented at the 2025 American Society of Clinical oncology (ASCO) meeting by Dr. Timothy Cannon and colleagues at the Inova Schar Cancer Institute, examined the colon health of 100 healthy runners aged 35-50. All participants had completed at least five marathons or two ultramarathons and had never undergone a colonoscopy. Individuals with known risk factors for colon cancer, such as hereditary cancer syndromes or inflammatory bowel disease, were excluded from the study.
Concerning Findings
the study revealed that a significant 41% of participants had at least one adenoma, a type of polyp in the colon. Even more concerning, 15% had advanced adenomas – larger, more abnormal polyps with a higher likelihood of developing into cancer over time. This is significantly higher than the typical expected rate of 1-2% for this age group.The average age of participants was 42.5 years, wich is below the age at which many people begin routine colon cancer screening.
Association, Not Causation
It’s crucial to understand that this study demonstrates an association, not a direct cause-and-effect relationship. While the research suggests a link between extreme long-distance running and a higher prevalence of precancerous colon growths, it doesn’t prove that running causes colorectal cancer. Other factors could be at play.
The study also had limitations,including a relatively small sample size and the absence of a control group of non-runners under identical conditions. Moreover, the study didn’t fully control for factors like diet, genetics, training intensity, recovery, and gastrointestinal symptoms.
why the Potential Risk?
While the study doesn’t definitively explain the link, it offers some potential explanations. During extreme endurance events like marathons, blood flow is diverted away from the gut and towards the muscles. This can lead to gut ischemia (reduced blood flow to the intestines), which can cause inflammation and potentially contribute to the development of polyps.
What This Means for Runners
This study serves as a reminder that even the fittest individuals need to be mindful of their colon health