Marathon Runners Face Higher Colon Cancer Risk, Study Finds

A recent study indicates that individuals participating in marathons and ultramarathons might have a heightened risk for colon cancer. Oncologist Timothy Cannon observed three young, prolific runners with advanced colon cancer, prompting further investigation. His study, published in Cancer Epidemiology, examined 94 runners aged 35-50 who had completed multiple marathons or ultramarathons.

Colonoscopies revealed that nearly half of these runners had polyps, with about 15% presenting large polyps, which are considered further along the path to cancer. This incidence rate is significantly higher than in the general adult population of similar age. The study suggests that the sustained, extreme physical exertion during these races diverts blood from the gut to the muscles.

This reduced blood flow and oxygen to gut cells, coupled with the intense repair process after exercise, could lead to rapid cell replication and an increased possibility of mutations, polyps, and ultimately, cancer. While the study is preliminary and lacked a control group, researchers urge runners to monitor for gastrointestinal abnormalities like rectal bleeding and consult a doctor if concerns arise.