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Marathon Runners Face Increased Risk of Colon Cancer Precursors, Study Suggests

From Liberty Times · () Chinese

Translated from Chinese, summarized and contextualized by DistantNews.

At a glance

News Named sources Context piece
  • A study on long-distance runners found a high prevalence of colon polyps, with 15% having precancerous adenomas.
  • Researchers suggest prolonged running may cause colon ischemia, and frequent consumption of energy gels could be contributing factors.
  • The findings raise concerns about potential risks associated with extensive marathon running, despite exercise generally being considered healthy.

While exercise is widely recognized for its health benefits, a recent study focusing on long-distance runners suggests a potential, albeit concerning, link between extensive marathon running and an increased risk of colon cancer precursors.

Researchers at the Inova Schar Cancer Institute in the United States conducted a prospective study involving 100 runners aged 35 to 50 who had completed at least five marathons or two ultramarathons. The study, presented at the 2025 American Society of Clinical Oncology (ASCO) annual meeting, revealed that nearly 41% of participants had at least one colon polyp, and a significant 15% were found to have advanced adenomas, which are considered precancerous lesions.

These findings are particularly striking when compared to the general population. The expected incidence of advanced adenomas in individuals aged 40-49 is around 1.2%. The study indicates that these athletes face more than ten times the risk of developing such precancerous conditions.

The study found that nearly 41% of participants had at least one adenoma, and 15% had advanced adenomas (precancerous lesions of the colon).

— Keelung Chang Gung Memorial HospitalDr. Chien Cheng-hung of Keelung Chang Gung Memorial Hospital's Department of Gastroenterology and Hepatology shared findings from a study on long-distance runners.

Two primary factors are hypothesized to contribute to this elevated risk. Firstly, prolonged running may lead to colon ischemia, a condition where blood flow to the colon is reduced due to blood being diverted to the limbs during intense physical activity. This repeated low-oxygen stimulation and inflammation cycle could theoretically promote the development of polyps and precancerous changes.

Secondly, many long-distance runners rely on energy gels to maintain their stamina. These products are often classified as "ultra-processed foods." The researchers theorize that consuming these gels when the colon's lining is already compromised by hypoxia and injury might pose health risks. While these hypotheses require further validation, the study highlights a potential area of concern for the athletic community.

The potential risks are worth noting, even if these arguments have not yet been proven.

— Keelung Chang Gung Memorial HospitalDr. Chien Cheng-hung emphasized the need for attention to these potential risks despite the lack of definitive proof.
DistantNews Editorial

Originally published by Liberty Times in Chinese. Translated, summarized, and contextualized by our editorial team with added local perspective. Read our editorial standards.

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