Gastrointestinal bleeding and the risk of colorectal cancer in anticoagulated patients with atrial fibrillation

Peter Vibe Rasmussen*, Frederik Dalgaard, Gunnar Hilmar Gislason, Axel Brandes, Søren Paaske Johnsen, Erik Lerkevang Grove, Christian Torp-Pedersen, Lars Dybro, Louise Harboe, Anna-Marie Bloch Münster, Lasse Pedersen, Paul Blanche, Jannik Langtved Pallisgaard, Morten Lock Hansen

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review


AIMS: Gastrointestinal bleeding (GI-bleeding) is frequent in patients with atrial fibrillation (AF) treated with oral anticoagulation (OAC) therapy. We sought to investigate to what extent lower GI-bleeding represents the unmasking of an occult colorectal cancer.

METHODS AND RESULTS: A total of 125 418 Danish AF patients initiating OAC therapy were identified using Danish administrative registers. Non-parametric estimation and semi-parametric absolute risk regression were used to estimate the absolute risks of colorectal cancer in patients with and without lower GI-bleeding. During a maximum of 3 years of follow-up, we identified 2576 patients with lower GI-bleeding of whom 140 patients were subsequently diagnosed with colorectal cancer within the first year of lower GI-bleeding. In all age groups, we observed high risks of colorectal cancer after lower GI-bleeding. The absolute 1-year risk ranged from 3.7% [95% confidence interval (CI) 2.2-6.2] to 8.1% (95% CI 6.1-10.6) in the age groups ≤65 and 76-80 years of age, respectively. When comparing patients with and without lower GI-bleeding, we found increased risk ratios of colorectal cancer across all age groups with a risk ratio of 24.2 (95% CI 14.5-40.4) and 12.3 (95% CI 7.9-19.0) for the youngest and oldest age group of ≤65 and >85 years, respectively.

CONCLUSION: In anticoagulated AF patients, lower GI-bleeding conferred high absolute risks of incident colorectal cancer. Lower GI-bleeding should not be dismissed as a benign consequence of OAC therapy but always examined for a potential underlying malignant cause.

Original languageEnglish
JournalEuropean Heart Journal
Issue number7
Pages (from-to)e38-e44
Publication statusPublished - 14. Feb 2022


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