title: Clopidogrel use and cancer-specific mortality: a population-based cohort study of colorectal, breast and prostate cancer patients.
abstract: OBJECTIVE
  Concerns were raised about the safety of antiplatelet thienopyridine derivatives after a randomized control trial reported increased risks of cancer and cancer deaths in prasugrel users. We investigate whether clopidogrel, a widely used thienopyridine derivative, was associated with increased risk of cancer-specific or all-cause mortality in cancer patients.
  
  
  METHODS
  Colorectal, breast and prostate cancer patients, newly diagnosed from 1998 to 2009, were identified from the National Cancer Data Repository. Cohorts were linked to the UK Clinical Practice Research Datalink, providing prescription records, and to the Office of National Statistics mortality data (up to 2012). Unadjusted and adjusted hazard ratios (HRs) for cancer-specific and all-cause mortality in post-diagnostic clopidogrel users were calculated using time-dependent Cox regression models.
  
  
  RESULTS
  The analysis included 10 359 colorectal, 17 889 breast and 13 155 prostate cancer patients. There was no evidence of an increase in cancer-specific mortality in clopidogrel users with colorectal (HR = 0.98 95% confidence interval (CI) 0.77, 1.24) or prostate cancer (HR = 1.03 95%CI 0.82, 1.28). There was limited evidence of an increase in breast cancer patients (HR = 1.22 95%CI 0.90, 1.65); however, this was attenuated when removing prescriptions in the year prior to death.
  
  
  CONCLUSIONS
  This novel study of large population-based cohorts of colorectal, breast and prostate cancer patients found no evidence of an increased risk of cancer-specific mortality among colorectal, breast and prostate cancer patients using clopidogrel.
authors.affiliation: Cancer Epidemiology and Health Services Research Group, Centre for Public Health, Queen's University Belfast, Belfast, UK.
authors.forename: Blánaid M
authors.initials: BM
authors.lastname: Hicks
authors.affiliation: Cancer Epidemiology and Health Services Research Group, Centre for Public Health, Queen's University Belfast, Belfast, UK.|Centre of Excellence for Public Health (NI), Centre for Public Health, Queen's University Belfast, Belfast, UK.
authors.forename: Liam J
authors.initials: LJ
authors.lastname: Murray
authors.affiliation: School of Pharmacy, Queen's University Belfast, Belfast, UK.
authors.forename: Carmel
authors.initials: C
authors.lastname: Hughes
authors.affiliation: Cancer Epidemiology and Health Services Research Group, Centre for Public Health, Queen's University Belfast, Belfast, UK.
authors.forename: Chris R
authors.initials: CR
authors.lastname: Cardwell
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000175:diagnosis / Q000401:mortality*; D002423:Cause of Death; D000077144:Clopidogrel; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000401:mortality*; D016208:Databases, Factual; D011307:Drug Prescriptions; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D061214:Patient Safety; D017891:Pharmacoepidemiology; D010975:Platelet Aggregation Inhibitors / Q000009:adverse effects*; D016016:Proportional Hazards Models; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000401:mortality*; D018570:Risk Assessment; D012307:Risk Factors; D013988:Ticlopidine / Q000009:adverse effects / Q000031:analogs & derivatives*; D013997:Time Factors; D016896:Treatment Outcome; D006113:United Kingdom / Q000453:epidemiology
chemical_list: D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine
keywords: antiplatelet; breast neoplasm; clopidogrel; colorectal neoplasms; pharmacoepidemiology; prostate neoplasms