title: Body Mass Index and Risk of Gallbladder Cancer: Systematic Review and Meta-Analysis of Observational Studies.
abstract: OBJECTIVE
  To provide a quantitative assessment of the association between excess body weight, interpreted as increased body mass index (BMI), and the risk of gallbladder cancer (GBC).
  
  
  METHODS
  We identified eligible studies in Medline and EMBASE up to 1 February 2015, and reference lists of retrieved articles. Summary relative risks with their 95% confidence intervals were calculated in a random-effects model. Subgroup analyses were performed according to study design, gender, geographic location, ascertainment of exposure and adjustment for confounders.
  
  
  RESULTS
  A total of 12 cohort studies and 8 case-control studies were included in the meta-analysis. Overall, compared with "normal" weight, the summary relative risks of GBC were 1.14 (95% CI, 1.04-1.25) for overweight individuals (BMI 25-30 kg/m²) and 1.56 (95% CI, 1.41-1.73) for obese individuals (BMI > 30 kg/m²). Obese women had a higher risk of GBC than men did (women: SRRs 1.67, 95% CI 1.38-2.02; men: SRRs 1.42, 95% CI 1.21-1.66), and there was significant association between overweight and GBC risk in women (SRRs 1.26, 95% CI 1.13-1.40), but not in men (SRRs 1.06, 95% CI 0.94-1.20).
  
  
  CONCLUSIONS
  Findings from this meta-analysis indicate that obesity is associated with an increased risk of GBC, especially in women. Overweight is associated with GBC risk only in women.
authors.affiliation: Department of Basical Medicine, Jining Medical University, 16 Hehua Road, Jining 272067, China. lzhzsdxsyx@gmail.com.
authors.forename: Wenbin
authors.initials: W
authors.lastname: Tan
authors.affiliation: Department of Clinical Laboratory, Jining NO.1 People's Hospital, 6 Jiankang Road, Jining 272011, China. medchenjun@126.com.
authors.forename: Min
authors.initials: M
authors.lastname: Gao
authors.affiliation: Department of Information Technology, Jining Medical University, 16 Hehua Road, Jining 272067, China. liuningsci@126.com.
authors.forename: Ning
authors.initials: N
authors.lastname: Liu
authors.affiliation: Department of Pathology, Jining Medical University, 16 Hehua Road, Jining 272067, China. zga2007@126.com.
authors.forename: Guoan
authors.initials: G
authors.lastname: Zhang
authors.affiliation: Department of Gastrointestinal Surgery, Affiliated Hospital of Jining Medical University, 79 Guhuai Road, Jining 272029, China. ciwinglee@126.com.
authors.forename: Tong
authors.initials: T
authors.lastname: Xu
authors.affiliation: Department of Pathology, Jining Medical University, 16 Hehua Road, Jining 272067, China. cuiwenmd@sina.com.
authors.forename: Wen
authors.initials: W
authors.lastname: Cui
mesh_terms: D015992:Body Mass Index; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D005706:Gallbladder Neoplasms / Q000453:epidemiology* / Q000209:etiology; D042882:Gallstones / Q000150:complications; D020022:Genetic Predisposition to Disease; D006801:Humans; D016239:MEDLINE; D008297:Male; D009765:Obesity / Q000150:complications; D050177:Overweight / Q000150:complications; D012306:Risk; D012307:Risk Factors; D012737:Sex Factors
keywords: body mass index; gallbladder cancer; meta-analysis; obesity; overweight