Key clinical point: The effect of warfarin treatment on the risk of prostate cancer is likely the result of detection bias from lower rates of biopsies among men who are anticoagulated.
Major finding: Incidence and rates of prostate biopsies decreased over time in the general population group vs the anticoagulation group among men enrolled in 2008-2010.
Study details: Trends were compared in prostate cancer incidence between 17,815 men treated with chronic oral anticoagulation for prosthetic heart valve thromboprophylaxis and a general population comparison group of 356,300 men.
Ward MM. Int J Cancer. 2019 Oct 3. doi: 10.1002/ijc.32712.
Previously, studies have suggested a potential association between warfarin use and a lower risk of prostate cancer. However, a clear mechanism of association has yet to become obvious. Many of these studies were retrospective cohort studies that have many limitations, one of which includes detection bias. In this study, the author conducted a cohort study comparing patients receiving anticoagulation for heart valves with a matched population receiving no anticoagulation to evaluate for detection bias. Over time, the difference in the incidence of prostate cancer between the two groups decreased, suggesting that detection bias may be one reason for the association. —Mark A. Klein, MD