Risk of colorectal cancer in patients with acute myocardial infarction and stroke: A nationwide cohort study
Couplée avec les données des registres nationaux, cette étude de cohorte en population danoise évalue l'association entre un infarctus aigu du myocarde, un accident vasculaire cérébral et le risque de cancer colorectal, sur la période 1978-2010
Background: An association between colorectal cancer (CRC) and acute myocardial infarction (AMI) and stroke has been suggested, but evidence is conflicting. Method: We conducted a population-based cohort study (1978-2010) of the association between AMI/stroke and CRC by linking nationwide Danish registries. We calculated standardized incidence ratios (SIRs) of CRC after AMI/stroke as the ratios of observed to expected incidence. Results: 297,523 AMI patients (median age 69.4, 64% men) were followed for a median of 3.1 years (range 0-33 years) and 4,387 developed CRC (SIR=1.08, 95% CI: 1.05-1.11, p<0.001). In the first year of follow-up the SIR was 1.85 (95% CI: 1.73-1.98, p<0.001) while it was 0.98 (95% CI: 0.95-1.02, p=0.318) in the second and subsequent years. We followed 246,998 stroke patients (median age 72.4, 52% men) for a median of 2.9 years (range 0-33 years) and 3,035 developed CRC (SIR 1.04, 95% CI: 1.00-1.07, p=0.053). In the first year of follow-up the SIR was 1.42 (95% CI: 1.31-1.53, p<0.001) while it was 0.96 (95% CI: 0.93-1.00, p=0.072) thereafter. We found no difference between the SIRs for ischemic and hemorrhagic stroke. The increased one-year relative risks for AMI and stroke corresponded to a 0.3% absolute risk. Conclusion: Our findings reflect detection of occult cancer at the time of the vascular event. The lack of increased risk after one year suggests that an association based on shared risk factors or chronic inflammation is unlikely. Impact: In AMI/stroke patients the diagnostic workup including screening for CRC should follow that of the general population.