title: Gender as a risk factor for advanced neoplasia and colorectal cancer: a systematic review and meta-analysis.
abstract: OBJECTIVE
  Studies have reported higher rates of advanced colorectal neoplasia in men than in women. We performed a meta-analysis to provide a quantitative pooled risk estimate of the association between gender and advanced colorectal neoplasia.
  
  
  METHODS
  We conducted a systematic review to identify studies of average risk and asymptomatic individuals undergoing screening colonoscopy. We also included studies of subjects with a family history of colorectal neoplasia. We used random effects models to evaluate pooled relative risk estimates and performed heterogeneity and publication bias analyses. The primary outcome measure was relative risk of advanced neoplasia in men compared with women. A secondary outcome measure was relative risk for colorectal cancer.
  
  
  RESULTS
  Seventeen studies consisting of 18 different populations were included, comprising 924,932 men and women. The pooled relative risk estimate for advanced neoplasia for men compared with women was 1.83 (95% confidence interval [CI], 1.69 -1.97). This positive association between gender and advanced neoplasia was significant across all age groups from 40 to older than 70 years. In 5 studies, the relative risk estimate for cancer for men compared with women was 2.02 (95% CI, 1.53-2.66). Significant heterogeneity was found for the overall analysis and for studies reporting on cancer but not for studies thate xcluded subjects with a family history or for those analyses grouped by age.
  
  
  CONCLUSIONS
  This meta-analysis provides strong evidence that men are at greater risk for advanced colorectal neoplasia across all age groups. This might inform decisions to create sex-specific colorectal cancer screening recommendations.
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of California, San Francisco, San Francisco, California 94143, USA.
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Nguyen
authors.forename: Stephen
authors.initials: S
authors.lastname: Bent
authors.forename: Yea-Hung
authors.initials: YH
authors.lastname: Chen
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Terdiman
mesh_terms: D000328:Adult; D000368:Aged; D015179:Colorectal Neoplasms / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012737:Sex Factors