title: Warfarin use and prostate cancer risk in the Finnish Randomized Study of Screening for Prostate Cancer.
abstract: OBJECTIVE
  Anticoagulants, especially vitamin K antagonists (VKAs) such as warfarin, have been hypothesized to have antitumor properties, and use of VKAs has been associated with a lower prostate cancer (PCa) risk. This study estimated PCa risk among users of warfarin and other anticoagulants.
  
  
  METHODS
  All anticoagulant use among 78,615 men during 1995-2009 was analyzed. Cox regression, adjusted for age, screening trial arm and use of other medications, with medication use as a time-dependent variable, was used to estimate PCa risk overall, and by tumor grade and stage.
  
  
  RESULTS
  In total, 6537 men were diagnosed with PCa during 1995-2009 (1210 among warfarin users). Compared to non-users, warfarin use was associated with an increased risk of PCa [multivariable-adjusted hazard ratio (HR) = 1.11, 95% confidence interval (CI) 1.01-1.22]. This was limited to short-term, low-dose use, and was not observed in long-term use. A similar overall risk increase was observed for Gleason grade 7-10 PCa. Low-dose, short-term use of warfarin was associated with an increased risk of metastatic PCa. However, the increase in risk vanished with continued use. Compared to other anticoagulants, low-dose use of warfarin was associated with a slightly elevated overall PCa risk (HR = 1.19, 95% CI 1.00-1.43). The increase in risk disappeared in long-term, high-dose use.
  
  
  CONCLUSIONS
  This study, which included a larger number of PCa cases with warfarin exposure than previous studies, does not support previous notions of decreased risk of PCa among warfarin users. A similar risk of PCa was found among warfarin users and the general population, and no difference in risk was found between warfarin and other anticoagulants.
authors.affiliation: a School of Medicine , University of Tampere , Tampere , Finland.
authors.forename: Pete T T
authors.initials: PT
authors.lastname: Kinnunen
authors.affiliation: a School of Medicine , University of Tampere , Tampere , Finland.|b Department of Urology , Tampere University Hospital , Tampere , Finland.
authors.forename: Teemu J
authors.initials: TJ
authors.lastname: Murtola
authors.affiliation: c Finnish Cancer Registry , Helsinki , Finland.
authors.forename: Kirsi
authors.initials: K
authors.lastname: Talala
authors.affiliation: d Department of Urology , University of Helsinki and Helsinki University Hospital , Helsinki , Finland.
authors.forename: Kimmo
authors.initials: K
authors.lastname: Taari
authors.affiliation: a School of Medicine , University of Tampere , Tampere , Finland.|b Department of Urology , Tampere University Hospital , Tampere , Finland.
authors.forename: Teuvo L J
authors.initials: TL
authors.lastname: Tammela
authors.affiliation: e School of Health Sciences , University of Tampere , Tampere , Finland.
authors.forename: Anssi
authors.initials: A
authors.lastname: Auvinen
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage*; D055088:Early Detection of Cancer; D005387:Finland / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009362:Neoplasm Metastasis; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000473:pathology*; D012307:Risk Factors; D013997:Time Factors; D014859:Warfarin / Q000008:administration & dosage*
chemical_list: D000925:Anticoagulants; D014859:Warfarin
keywords: Anticoagulant drugs; cohort; metastasis; prostate cancer; risk; warfarin