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

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 - Feb 2022


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