title: Cancer risk related to low-dose ionizing radiation from cardiac imaging in patients after acute myocardial infarction.
abstract: BACKGROUND
  Patients exposed to low-dose ionizing radiation from cardiac imaging and therapeutic procedures after acute myocardial infarction may be at increased risk of cancer.
  
  
  METHODS
  Using an administrative database, we selected a cohort of patients who had an acute myocardial infarction between April 1996 and March 2006 and no history of cancer. We documented all cardiac imaging and therapeutic procedures involving low-dose ionizing radiation. The primary outcome was risk of cancer. Statistical analyses were performed using a time-dependent Cox model adjusted for age, sex and exposure to low-dose ionizing radiation from noncardiac imaging to account for work-up of cancer.
  
  
  RESULTS
  Of the 82,861 patients included in the cohort, 77% underwent at least one cardiac imaging or therapeutic procedure involving low-dose ionizing radiation in the first year after acute myocardial infarction. The cumulative exposure to radiation from cardiac procedures was 5.3 milliSieverts (mSv) per patient-year, of which 84% occurred during the first year after acute myocardial infarction. A total of 12 020 incident cancers were diagnosed during the follow-up period. There was a dose-dependent relation between exposure to radiation from cardiac procedures and subsequent risk of cancer. For every 10 mSv of low-dose ionizing radiation, there was a 3% increase in the risk of age- and sex-adjusted cancer over a mean follow-up period of five years (hazard ratio 1.003 per milliSievert, 95% confidence interval 1.002-1.004).
  
  
  CONCLUSIONS
  Exposure to low-dose ionizing radiation from cardiac imaging and therapeutic procedures after acute myocardial infarction is associated with an increased risk of cancer.
authors.affiliation: Division of Cardiology, Jewish General Hospital, Montréal, Que.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Eisenberg
authors.forename: Jonathan
authors.initials: J
authors.lastname: Afilalo
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Lawler
authors.forename: Michal
authors.initials: M
authors.lastname: Abrahamowicz
authors.forename: Hugues
authors.initials: H
authors.lastname: Richard
authors.forename: Louise
authors.initials: L
authors.lastname: Pilote
mesh_terms: D000368:Aged; D003952:Diagnostic Imaging / Q000009:adverse effects*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging*; D009381:Neoplasms, Radiation-Induced / Q000209:etiology* / Q000517:prevention & control; D016016:Proportional Hazards Models; D011829:Radiation Dosage; D011835:Radiation Protection; D011859:Radiography; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors