title: Aspirin and cancer risk: a quantitative review to 2011.
abstract: BACKGROUND
  Aspirin has been associated to a reduced risk of colorectal and possibly of a few other common cancers.
  
  
  METHODS
  To provide an up-to-date quantification of this association, we conducted a meta-analysis of all observational studies on aspirin and 12 selected cancer sites published up to September 2011.
  
  
  RESULTS
  Regular aspirin is associated with a statistically significant reduced risk of colorectal cancer [summary relative risk (RR) from random effects models = 0.73, 95% confidence interval (CI) 0.67-0.79], and of other digestive tract cancers (RR = 0.61, 95% CI = 0.50-0.76, for squamous cell esophageal cancer; RR = 0.64, 95% CI = 0.52-0.78, for esophageal and gastric cardia adenocarcinoma; and RR = 0.67, 95% CI = 0.54-0.83, for gastric cancer), with somewhat stronger reductions in risk in case-control than in cohort studies. Modest inverse associations were also observed for breast (RR = 0.90, 95% CI = 0.85-0.95) and prostate cancer (RR = 0.90, 95% CI = 0.85-0.96), while lung cancer was significantly reduced in case-control studies (0.73, 95% CI = 0.55-0.98) but not in cohort ones (RR = 0.98, 95% CI = 0.92-1.05). No meaningful overall associations were observed for cancers of the pancreas, endometrium, ovary, bladder, and kidney.
  
  
  CONCLUSIONS
  Observational studies indicate a beneficial role of aspirin on colorectal and other digestive tract cancers; modest risk reductions were also observed for breast and prostate cancer. Results are, however, heterogeneous across studies and dose-risk and duration-risk relationships are still unclear.
authors.affiliation: Department of Epidemiology, Istituto di Ricerche Farmacologiche, Mario Negri, Milan, Italy. cristina.bosetti@marionegri.it
authors.forename: C
authors.initials: C
authors.lastname: Bosetti
authors.forename: V
authors.initials: V
authors.lastname: Rosato
authors.forename: S
authors.initials: S
authors.lastname: Gallus
authors.forename: J
authors.initials: J
authors.lastname: Cuzick
authors.forename: C
authors.initials: C
authors.lastname: La Vecchia
mesh_terms: D001241:Aspirin / Q000494:pharmacology*; D006801:Humans; D009369:Neoplasms / Q000517:prevention & control*; D012306:Risk
chemical_list: D001241:Aspirin