title: Aspirin use after diagnosis but not prediagnosis improves established colorectal cancer survival: a meta-analysis.
abstract: OBJECTIVE
  The objective of this meta-analysis was to systematically assess the survival benefit of aspirin use before or after diagnosis for patients with colorectal cancer (CRC).
  
  
  METHODS
  Relevant studies were identified through searching PubMed, Embase and Cochrane databases before May 2014. Two investigators extracted data independently for baseline characteristics and outcomes from the included studies. Either a fixed-effects or a random-effects model was derived to composite the pooled HR for overall mortality and CRC-specific mortality of CRC.
  
  
  RESULTS
  Seven studies on postdiagnosis aspirin therapy and seven studies on prediagnosis aspirin use were finally included in this meta-analysis. The overall survival benefit associated with postdiagnosis aspirin use represented an HR of 0.84 (95% CI 0.75 to 0.94). This effect was observed both in colon cancer (HR=0.78, 95% CI 0.64 to 0.96) and in rectal cancer (HR=0.90, 95% CI 0.83 to 0.98). Besides, the survival benefit of postdiagnosis aspirin use appeared to be confined to those patients with positive prostaglandin endoperoxide synthase 2 (PTGS2, also known as cyclooxygenase-2, COX-2) expression (HR=0.65, 95% CI 0.50 to 0.85) and with mutated PIK3CA tumours (HR=0.58, 95% CI 0.37 to 0.90). Aspirin use postdiagnosis was not associated with CRC-specific mortality (HR=0.77, 95% CI 0.52 to 1.14). We observed no evidence of an association between prediagnosis aspirin use and CRC overall mortality (HR=1.01, 95% CI 0.96 to 1.06) or CRC-specific mortality (HR=0.93, 95% CI 0.82 to 1.05).
  
  
  CONCLUSIONS
  These findings provide further indication that postdiagnosis aspirin therapy improved CRC overall survival, especially for patients with positive PTGS2 (COX-2) expression and mutated PIK3CA tumours.
authors.affiliation: Department of Epidemiology and Health Statistics, Zhejiang University School of Public Health, Hangzhou, China Department of Gastroenterology, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Peiwei
authors.initials: P
authors.lastname: Li
authors.affiliation: The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Han
authors.initials: H
authors.lastname: Wu
authors.affiliation: Department of Pathology, Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Honghe
authors.initials: H
authors.lastname: Zhang
authors.affiliation: State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Shi
authors.affiliation: Department of Epidemiology and Health Statistics, Zhejiang University School of Public Health, Hangzhou, China.
authors.forename: Jinming
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Epidemiology and Health Statistics, Zhejiang University School of Public Health, Hangzhou, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Ye
authors.affiliation: Department of Epidemiology and Health Statistics, Zhejiang University School of Public Health, Hangzhou, China.
authors.forename: Dajing
authors.initials: D
authors.lastname: Xia
authors.affiliation: State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China Department of Biomedicine, College of Biotechnology, Zhejiang Agriculture and Forestry University, Hangzhou, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Gastroenterology, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Jianting
authors.initials: J
authors.lastname: Cai
authors.affiliation: Department of Epidemiology and Health Statistics, Zhejiang University School of Public Health, Hangzhou, China.
authors.forename: Yihua
authors.initials: Y
authors.lastname: Wu
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis / Q000235:genetics / Q000401:mortality / Q000517:prevention & control; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage*; D001241:Aspirin / Q000008:administration & dosage*; D002423:Cause of Death; D058534:Class I Phosphatidylinositol 3-Kinases; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000401:mortality* / Q000517:prevention & control; D051546:Cyclooxygenase 2 / Q000235:genetics; D004334:Drug Administration Schedule; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics; D011379:Prognosis; D016032:Randomized Controlled Trials as Topic; D018570:Risk Assessment; D016019:Survival Analysis
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D019869:Phosphatidylinositol 3-Kinases; D058534:Class I Phosphatidylinositol 3-Kinases; C484760:PIK3CA protein, human; D001241:Aspirin
keywords: COLORECTAL CANCER