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.
Keywords: Atrial fibrillation; Colorectal cancer; Gastrointestinal bleeding; Oral anticoagulation.
Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: firstname.lastname@example.org.
Systemic Octreotide Therapy in Prevention of Gastrointestinal Bleeds Related to Arteriovenous Malformations and Obscure Etiology in Atrial Fibrillation.JACC Clin Electrophysiol. 2017 Dec 11;3(12):1390-1399. doi: 10.1016/j.jacep.2017.04.022. Epub 2017 Sep 13. JACC Clin Electrophysiol. 2017. PMID: 29759670 Clinical Trial.
Lower Gastrointestinal Bleeding And Risk of Gastrointestinal Cancer.Clin Transl Gastroenterol. 2016 Apr 7;7(4):e162. doi: 10.1038/ctg.2016.16. Clin Transl Gastroenterol. 2016. PMID: 27054580 Free PMC article.
Predictors of gastrointestinal bleeding among patients with atrial fibrillation after initiating dabigatran therapy.Pharmacotherapy. 2015 Jun;35(6):560-8. doi: 10.1002/phar.1597. Epub 2015 Jun 4. Pharmacotherapy. 2015. PMID: 26044889 Free PMC article.
Restarting oral anticoagulant therapy after major bleeding in atrial fibrillation: A systematic review and meta-analysis.Int J Cardiol. 2018 Jun 15;261:84-91. doi: 10.1016/j.ijcard.2018.03.053. Epub 2018 Mar 14. Int J Cardiol. 2018. PMID: 29572080 Review.
Reasons for undertreatment with oral anticoagulants in frail geriatric outpatients with atrial fibrillation: a prospective, descriptive study.Drugs Aging. 2010 Jan 1;27(1):39-50. doi: 10.2165/11319540-000000000-00000. Drugs Aging. 2010. PMID: 20030431 Review.