Advanced adenomas among young endurance runners: A prospective hypothesis-generating prevalence study

Abstract

Background: Extreme long-distance running can produce recurrent gastrointestinal stress, including splanchnic hypoperfusion, mucosal injury, and post-exercise rectal bleeding, but its relationship to colorectal neoplasia is unclear. We therefore prospectively estimated the prevalence of advanced adenomas in endurance runners aged 35–50 years. This prevalence estimate is hypothesis-generating. Methods: In this prospective, single-center, single-arm prevalence (cross-sectional) study (NCT05419531), participants had completed at least 2 ultramarathons (50 km or longer) or at least 5 marathons and had no colonoscopy within 10 years; key exclusions were inflammatory bowel disease, familial adenomatous polyposis, or Lynch syndrome. Participants completed a questionnaire and underwent colonoscopy. Advanced adenomas were defined as lesions 10 mm or larger, villous or tubulovillous histology (or > 25% villous component), or high-grade dysplasia. Prevalence was compared with a 1.2% historical rate reported in asymptomatic, average-risk adults aged 40–49 undergoing screening colonoscopy. Results: Participants were recruited and consented from November 2022 to November 2024, and 94 participants (54.3% female; median age, 42 years) underwent colonoscopy between December 2022 and January 2025. Adenomas were found in 39 participants (41.5%), and advanced adenomas in 14 (15.0%; 95% binomial CI, 8.4–23.7%); no cancers were detected. Most advanced lesions were right-sided. The average number of adenomas per participant with non-advanced adenomatous polyps was 1.8. The average number of adenomas found amongst the participants with advanced adenomas was slightly higher at 2.2. Conclusions: In this endurance-runner sample, advanced adenomas were observed at a prevalence of 15.0% overall. Compared with historical screening benchmarks, prevalence appeared higher, supporting further evaluation of colorectal neoplasia risk in endurance runners. However, differences in symptom profile and other risk factors between this study population and historical screening populations limit direct comparability, and the findings should be considered hypothesis-generating. Larger controlled studies and mechanistic work are needed. Trial registration: ClinicalTrials.gov NCT05419531.