title: Effect of 5-aminosalicylate use on colorectal cancer and dysplasia risk: a systematic review and metaanalysis of observational studies.
abstract: OBJECTIVE
  We performed a systematic review with metaanalysis of observational studies evaluating the association between 5-ASA use and colorectal cancer (CRC) or dysplasia among patients with ulcerative colitis.
  
  
  METHODS
  We conducted a search of Medline Embase Biosis, Web of Science, Cochrane Collaboration, manually reviewed the literature, and consulted with experts. Studies were included if they 1) evaluated and clearly defined exposure to 5-aminosalicylates in patients with ulcerative colitis, 2) reported CRC or dysplasia outcomes, 3) reported relative risks or odds ratio or provided data for their calculations. Quantitative analysis using a random-effects model is presented.
  
  
  RESULTS
  Nine studies (3 cohort, 6 case-control) containing 334 cases of CRC, 140 cases of dysplasia, and a total of 1,932 subjects satisfied all inclusion criteria. Five studies reported CRC outcomes alone, two studies reported separate cancer and dysplasia outcomes, and two studies reported a combined outcome of CRC or dysplasia. All primary estimates are homogenous. Pooled analysis showed a protective association between use of 5-aminosalicylates and CRC (OR=0.51; 95% confidence interval (CI): 0.37-0.69) or a combined endpoint of CRC/dysplasia (OR 0.51; 95% CI: 0.38-0.69). 5-ASA use was not associated with a lower risk of dysplasia, although only two studies evaluated this outcome (OR=1.18; 95% CI: 0.41-3.43).
  
  
  CONCLUSIONS
  Pooled results of observational studies support a protective association between 5-aminosalicylates and CRC or a combined endpoint of CRC/dysplasia in patients with ulcerative colitis. Additional studies analyzing the effect of 5-ASA on risk of dysplasia are needed.
authors.affiliation: Division of Gastroenterology and UCSF Center for Colitis and Crohn's Disease, University of California, San Francisco, California 94143, USA.
authors.forename: Fernando S
authors.initials: FS
authors.lastname: Velayos
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Terdiman
authors.forename: Judith M
authors.initials: JM
authors.lastname: Walsh
mesh_terms: D000328:Adult; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use*; D002986:Clinical Trials as Topic; D003093:Colitis, Ulcerative / Q000188:drug therapy / Q000473:pathology; D015179:Colorectal Neoplasms / Q000473:pathology* / Q000517:prevention & control*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D019804:Mesalamine / Q000627:therapeutic use*; D008875:Middle Aged; D015233:Models, Statistical; D019370:Observation; D017594:Publication Bias; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D019804:Mesalamine