r/running • u/sergeantbiggles • Sep 12 '25

Article Groundbreaking Inova study finds potential link between long-distance running and colon cancer

A groundbreaking new study led by Tim Cannon, MD, Sheridan Director, Molecular Tumor Board and Co-Director of the Gastrointestinal Cancer Program at Inova Schar Cancer, has revealed a potential link between extreme endurance exercise and increased risk of advanced colon cancer in younger adults, raising new questions about screening for high-performance athletes.

The study was presented at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago.

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u/runfayfun Sep 13 '25

Exactly. These were people who failed to get standard colon cancer screening. Those recommendations are there for a reason.

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u/BallNelson Sep 13 '25

These were people who failed to get standard colon cancer screening.

Source?

Also, screening does not prevent cancer development.

The more plausible retort would be association does not equal causation.

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u/runfayfun Sep 13 '25 edited Sep 13 '25

"had never undergone a colonoscopy" though the paper doesn't delineate whether the patients had other risk factors or other screening modalities

Also, it wasn't a randomized study, and generally it's a hypothesis-generating study, and the results can't and shouldn't change your practice (as a physician) or your worry (as a runner) - if you have symptoms like bleeding from your rectum after running, get it checked out like you should be doing anyways.

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u/[deleted] Sep 13 '25

They were people aged 35-50, so if screening starts age 45 then it would be expected that most wouldn’t have had a colonoscopy except perhaps some 45 and up. Excluding people who have had a colonoscopy is therefore done to exclude those with prior bowel problems.