Earlier this summer, we reported on an exciting study that found colon cancer patients who participated in a three-year exercise coaching program experienced 28 percent fewer cancer recurrences and were 37 percent less likely to die from any cause. In other words, the results showed that exercise could be a powerful colon cancer cure. However, new research suggests that not all exercise is beneficial in trying to reduce your risk of this steadily rising cancer.
RELATED: Colon Cancer Vaccine Gets One Step Closer to Reality.
Research links running marathons to an increased colon cancer risk.
New research presented at an American Society of Clinical Oncology conference looked at the risk of pre-cancerous adenomas (an advanced polyp) in the colon in long-distance runners.
The study was led by Timothy Cannon, MD, an oncologist with Inova Schar Cancer in Fairfax, Virginia. As Cannon explained to The New York Times, his research was influenced by three of his patients, all of whom, despite being young (40 or under), physically active, and a healthy weight, came to him with advanced colon cancer and later passed away.
In itself, this isn’t completely shocking. After all, colon cancer is currently the deadliest cancer among young men and the second deadliest among young women. Moreover, colon cancer cases among Americans aged 30 to 34 have risen 71 percent.
But what Cannon did find shocking was that all three of his patients exercised more than most people. “Two regularly ran 100-mile ultramarathons, and one had completed 13 half-marathons in a single year,” the Times reported.
So, for his study, he enlisted 100 participants aged 35-50 who had completed at least two ultramarathons (50 km or longer) or five registered marathons (26.2 miles). None of them had a personal history or family history of colon cancer or related risk factors.
A panel of gastroenterologists, pathologists, and oncologists reviewed the participants’ colonoscopy results and determined the following:
- 39 percent had at least one polyp
- 15 percent had advanced adenomas (pre-cancerous)
The Times puts this in perspective by noting that the average rate of advanced adenomas in U.S. adults in their late 40s is between 4.5 percent and 6 percent.
RELATED: Experts Warn Colon Cancer Screenings May Need to Start at Age 40.
How does long-distance running influence colon cancer?
The current study only proves a connection between long-distance running and advanced adenomas, not a causation. It’s also important to note that this was a relatively small study. However, doctors still have theories as to how marathon running could influence colon cancer.
“I found additional reason to believe that there could be a connection between endurance sports and increased risk for colorectal cancer when I read research on the reduction of blood flow to the stomach, intestines, and nearby organs that often occurs during strenuous exercise,” Cannon wrote in 2022 when he began his research.
“Over the course of a 50-mile race — six or seven hours for an elite athlete — the body re-routes a significant amount of blood flow from the gut to the active muscles in legs,” he continued. “The loss of blood flow to the gut during this intensive exercise can cause ischemia, resulting in cellular damage, and a more disorderly and rapid process of cell turnover.”
However, other doctors hypothesize that the connection is more about long-distance runners being more likely to miss colon cancer symptoms.
As the Times explains, endurance runners “often develop gastrointestinal symptoms that they dismiss as benign,” including diarrhea and bloody stools. There’s even a term for it—runner’s trots—which refers to the sudden and frequent urge to go to the bathroom that often happens during or after a long run.
Cannon plans to continue his research to establish more concrete research on the connection between long-distance running and colon cancer.
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