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Thromb Haemost
DOI: 10.1055/a-2810-0347
Original Article: Coagulation and Fibrinolysis

Atrial Fibrillation, Anticoagulants, and CRC Outcomes: A Nationwide 20-Year Study

Autor*innen

  • Arnar S. Agustsson 

    1   Faculty of Medicine, University of Iceland, Reykjavik, Iceland

  • Sigurdis Haraldsdottir

    1   Faculty of Medicine, University of Iceland, Reykjavik, Iceland
    2   Department of Medical Oncology, Landspitali University Hospital of Iceland, Reykjavik, Iceland

  • Helgi Birgisson

    3   The Icelandic Cancer Registry, Reykjavik, Iceland

  • Sigrun H. Lund

    1   Faculty of Medicine, University of Iceland, Reykjavik, Iceland
    4   Faculty of Physical Science, University of Iceland, Reykjavik, Iceland

  • Arnar B. Ingason

    5   Department of Surgery, University of Vermont Larner College of Medicine, Burlington, Vermont, United States

  • Johann P. Hreinsson

    6   Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden

  • Einar S. Bjornsson

    1   Faculty of Medicine, University of Iceland, Reykjavik, Iceland
    7   Department of Internal Medicine, Landspitali University Hospital of Iceland, Reykjavik, Iceland

Funding Information The writing and preparation of this paper were supported and funded in part by the research grant of Eimskipasjodur at the University of Iceland (nr 96512) and the Scientific grant of Landspitali (nr A-2021-011).
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Graphical Abstract

Abstract

Background

Colorectal cancer (CRC) is a leading cause of cancer-related death and presents most often with occult or overt gastrointestinal bleeding (GIB). Oral anticoagulation (OAC) use has been hypothesized to increase the rate of GIB events and potentially cause early detection of CRC. This study aimed to investigate whether prior use of OAC could decrease overall or cancer-specific mortality in patients with CRC.

Methods

All patients with CRC in Iceland from 2000 to 2019 were identified from the Icelandic Cancer Registry. Through a detailed review of medical records, clinical data were obtained. Comorbidity was assessed using the Charlson comorbidity index. Inverse probability weighting was used to balance the study groups.

Results

Of 2,563 patients, 173 were taking OACs due to atrial fibrillation and were diagnosed with CRC. OAC users were predominantly older males with a higher comorbidity index. While staging was not significantly different, tumor size and lymph node metastases were different. After weighting, OAC users had a similar overall mortality (HR = 1.08; 95% CI, 0.91–1.28, p = 0.37), but lower CRC-specific mortality (HR = 0.75; 95% CI, 0.57–1.00, p = 0.046), specifically in the first 5 years. Cardiovascular mortality was significantly higher in OAC users.

Conclusion

Patients on OACs due to atrial fibrillation had lower CRC-specific mortality, suggesting that OAC use could be associated with survival benefits through early detection of CRC. However, these results should be interpreted carefully due to substantial competing cardiovascular mortality.

Keywords

colorectal cancer - oral anticoagulation - atrial fibrillation - early detection

Data Availability Statement

The data that support the findings of this study are available on request from the corresponding author (E.S.B.).


Ethical Approval

The study was approved by the National Bioethics Committee (Nr. VSN-14-162).


Supplementary Material



Publikationsverlauf

Eingereicht: 25. Juli 2025

Angenommen nach Revision: 10. Februar 2026

Artikel online veröffentlicht:
23. Februar 2026

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