Use of oral anticoagulants and risk of prostate cancer: a population-based case-control study in Montreal, Canada.

PURPOSE: A few recent epidemiological observations suggest that anticoagulant medications may protect against prostate cancer development. Most studies have been small or subjected to methodological issues, including potential confounding. We provide here new evidence on this association in the context of a population-based case-control study of prostate cancer conducted in Montreal, Canada.
METHODS: Cases were 1,588 men with incident prostate cancer, aged ≤75 years, diagnosed across French hospitals in the Montreal area between 2005 and 2009. Concurrently, 1,618 population controls from the same residential area and age distribution (±5 years) were randomly selected from the electoral list of French-speaking men. In-person interviews elicited information on socio-demographic, lifestyle and environmental factors, along with a detailed medical history. Unconditional logistic regression was used to assess the association between lifetime use of anticoagulants and prostate cancer risk.
RESULTS: 102 subjects (2.6 % of cases and 3.7 % of controls) reported a history of oral anticoagulant therapy. After controlling for age, ancestry, education, family history of prostate cancer, prostate cancer screening frequency, diabetes, body mass index and statin use, ever use of oral anticoagulants showed a weak inverse, non-statistically significant association with prostate cancer (odds ratio 0.76, 95% confidence interval 0.50-1.16). Similar results were observed in analyses considering duration of use or indication for use, restricted to subjects recently screened or stratified by cancer aggressiveness.
CONCLUSIONS: Our findings provide weak support for a protective effect of oral anticoagulant therapy against prostate cancer. Further confirmation is required, especially in light of potential bleeding complications associated with anticoagulants.