title: A randomized trial of aspirin to prevent colorectal adenomas in patients with previous colorectal cancer.
abstract: BACKGROUND
  Experimental studies in animals and observational studies in humans suggest that regular aspirin use may decrease the risk of colorectal adenomas, the precursors to most colorectal cancers.
  
  
  METHODS
  We conducted a randomized, double-blind trial to determine the effect of aspirin on the incidence of colorectal adenomas. We randomly assigned 635 patients with previous colorectal cancer to receive either 325 mg of aspirin per day or placebo. We determined the proportion of patients with adenomas, the number of recurrent adenomas, and the time to the development of adenoma between randomization and subsequent colonoscopic examinations. Relative risks were adjusted for age, sex, cancer stage, the number of colonoscopic examinations, and the time to a first colonoscopy. The study was terminated early by an independent data and safety monitoring board when statistically significant results were reported during a planned interim analysis.
  
  
  RESULTS
  A total of 517 randomized patients had at least one colonoscopic examination a median of 12.8 months after randomization. One or more adenomas were found in 17 percent of patients in the aspirin group and 27 percent of patients in the placebo group (P=0.004). The mean (+/-SD) number of adenomas was lower in the aspirin group than the placebo group (0.30+/-0.87 vs. 0.49+/-0.99, P=0.003 by the Wilcoxon test). The adjusted relative risk of any recurrent adenoma in the aspirin group, as compared with the placebo group, was 0.65 (95 percent confidence interval, 0.46 to 0.91). The time to the detection of a first adenoma was longer in the aspirin group than in the placebo group (hazard ratio for the detection of a new polyp, 0.64; 95 percent confidence interval, 0.43 to 0.94; P=0.022).
  
  
  CONCLUSIONS
  Daily use of aspirin is associated with a significant reduction in the incidence of colorectal adenomas in patients with previous colorectal cancer.
authors.affiliation: Department of Medicine, University of North Carolina, Chapel Hill 27599-7555, USA. rsandler@med.unc.edu
authors.forename: Robert S
authors.initials: RS
authors.lastname: Sandler
authors.forename: Susan
authors.initials: S
authors.lastname: Halabi
authors.forename: John A
authors.initials: JA
authors.lastname: Baron
authors.forename: Susan
authors.initials: S
authors.lastname: Budinger
authors.forename: Electra
authors.initials: E
authors.lastname: Paskett
authors.forename: Roger
authors.initials: R
authors.lastname: Keresztes
authors.forename: Nicholas
authors.initials: N
authors.lastname: Petrelli
authors.forename: J Marc
authors.initials: JM
authors.lastname: Pipas
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Karp
authors.forename: Charles L
authors.initials: CL
authors.lastname: Loprinzi
authors.forename: Gideon
authors.initials: G
authors.lastname: Steinbach
authors.forename: Richard
authors.initials: R
authors.lastname: Schilsky
mesh_terms: D000236:Adenoma / Q000401:mortality / Q000517:prevention & control*; D000328:Adult; D000368:Aged; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use*; D001241:Aspirin / Q000627:therapeutic use*; D003111:Colonic Polyps / Q000175:diagnosis / Q000517:prevention & control; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000401:mortality / Q000517:prevention & control*; D018572:Disease-Free Survival; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012306:Risk; D055502:Secondary Prevention
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D001241:Aspirin