A population-based cohort study of the risk of colorectal and other cancers among users of low-dose aspirin

Br J Cancer. 2003 Mar 10;88(5):684-8. doi: 10.1038/sj.bjc.6600760.


Using data from the population-based Prescription Database of North Jutland County and the Danish Cancer Registry, we compared cancer incidence among 29 470 individuals prescribed low-dose aspirin at maximum doses of 150 mg with expected incidence based on county-specific cancer rates, during a 9-year study period. We observed 2381 cancer cases compared with 2187 expected, yielding a standardised incidence ratio (SIR) of 1.09 (95% confidence interval (CI), 1.05-1.13). No apparent risk reductions were found for cancers of the colon (SIR, 0.9; 95% CI, 0.7-1.1) or rectum (SIR, 1.0; 95% CI, 0.8-1.2), or for other site-specific cancers. Increased SIRs were observed for kidney cancer (SIR, 1.4; 95% CI, 1.1-1.7) and brain cancer (SIR, 1.7; 95% CI, 1.3-2.2), although the excess in the latter was confined to the first year of follow-up. Stratification by number of prescriptions and duration of follow-up revealed no apparent trends. The SIR for colorectal cancer was close to unity (SIR, 0.9; 95% CI, 0.6-1.2) among persons with 10 or more prescriptions who were followed for at least 5 years. Our results do not support a major protective effect of low-dose aspirin on the development of colorectal or other cancers. The observed excesses of kidney and brain cancers are not likely to be causally related to the use of low-dose aspirin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aspirin / administration & dosage*
  • Cohort Studies
  • Colorectal Neoplasms / epidemiology*
  • Colorectal Neoplasms / prevention & control
  • Denmark / epidemiology
  • Dose-Response Relationship, Drug
  • Female
  • Humans
  • Incidence
  • Male
  • Middle Aged
  • Population Surveillance*
  • Risk Factors


  • Aspirin