title: The effect of warfarin therapy on breast, colorectal, lung, and prostate cancer survival: a population-based cohort study using the Clinical Practice Research Datalink.
abstract: OBJECTIVE
  Pre-clinical studies suggest that oral anticoagulant agents, such as warfarin, may inhibit metastases and potentially prolong survival in cancer patients. However, few population-based studies have examined the association between warfarin use and cancer-specific mortality.
  
  
  METHODS
  Using prescribing, cause of death, and cancer registration data from the UK Clinical Practice Research Datalink, four population-based cohorts were constructed, comprising breast, colorectal, lung, and prostate cancer patients diagnosed between 1 January 1998, and the 31 December 2010. Comparing pre-diagnostic warfarin users to non-users, multivariable Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95 % confidence intervals (CIs) for cancer-specific mortality.
  
  
  RESULTS
  Overall, 16,525 breast, 12,902 colorectal, 12,296 lung, and 12,772 prostate cancers were included. Pre-diagnostic warfarin use ranged from 2.4 to 4.7 %. There was little evidence of any strong association between warfarin use pre-diagnosis and cancer-specific mortality in prostate (adjusted HR 1.03, 95 % CI 0.84-1.26), lung (adjusted HR 1.06, 95 % CI 0.96-1.16), breast (adjusted HR 0.81, 95 % CI 0.62-1.07), or colorectal (adjusted HR 0.88, 95 % CI 0.77-1.01) cancer patients. Dose-response analyses did not reveal consistent evidence of reductions in users of warfarin defined by the number of prescriptions used and daily defined doses.
  
  
  CONCLUSIONS
  There was little evidence of associations between pre-diagnostic use of warfarin and cancer-specific mortality in lung, prostate, breast, or colorectal cancer patients.
authors.affiliation: Cancer Epidemiology and Health Services Research Group, Centre for Public Health, Queen's University Belfast, Institute of Clinical Sciences Block B, Royal Victoria Hospital Site, Grosvenor Road, Belfast, BT12 6BJ, UK, m.ororke@qub.ac.uk.
authors.forename: M A
authors.initials: MA
authors.lastname: O'Rorke
authors.forename: L J
authors.initials: LJ
authors.lastname: Murray
authors.forename: C M
authors.initials: CM
authors.lastname: Hughes
authors.forename: M M
authors.initials: MM
authors.lastname: Cantwell
authors.forename: C R
authors.initials: CR
authors.lastname: Cardwell
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy / Q000401:mortality*; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000401:mortality*; D016208:Databases, Factual; D005260:Female; D006801:Humans; D015994:Incidence; D008175:Lung Neoplasms / Q000188:drug therapy / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis / Q000188:drug therapy; D016016:Proportional Hazards Models; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000401:mortality*; D014859:Warfarin / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D014859:Warfarin