title: Body mass index and risk of primary liver cancer: a meta-analysis of prospective studies.
abstract: BACKGROUND
  Questions remain about the dose-response relationship between body mass index (BMI) and primary liver cancer (PLC) risk, possible confounding by hepatitis virus infection, and differences by gender or geographic location. We performed a meta-analysis of prospective studies to explore these issues.
  
  
  METHODS
  We searched PubMed and Embase for studies of BMI and risk of PLC through November 30, 2011. Summary relative risks with their corresponding 95% confidence intervals (CIs) were calculated using a random effects model.
  
  
  RESULTS
  A total of 21 prospective studies (including 17,624 PLC cases) were included in our analysis. The summary relative risk for a 5-unit increment in BMI (in kg/m(2)) was 1.39 (95% CI: 1.25-1.55), with high heterogeneity. These positive results were robust when stratified by sex, geographic location, ascertainment of exposure and outcome, the number of cases, duration of follow-up, sample source, and cofounders. There was evidence of a nonlinear association between BMI and PLC risk, with the most pronounced increase in risk among persons with a BMI >32 kg/m(2). Patients with hepatitis C virus or cirrhosis (but not patients with hepatitis B virus) with excess weight had a higher risk of PLC development than general populations with excess weight.
  
  
  CONCLUSIONS
  Excess weight increases PLC risk. For people with HCV infection or cirrhosis, risk increases are greater than for general population.
authors.affiliation: Department of Gastroenterology, Xinhua Hospital, Shanghai Jiaotong University, School of Medicine, 1665 Kongjiang Road, Shanghai, People's Republic of China.
authors.forename: Yuqin
authors.initials: Y
authors.lastname: Wang
authors.forename: Baochan
authors.initials: B
authors.lastname: Wang
authors.forename: Feng
authors.initials: F
authors.lastname: Shen
authors.forename: Jiangao
authors.initials: J
authors.lastname: Fan
authors.forename: Haixia
authors.initials: H
authors.lastname: Cao
mesh_terms: D015992:Body Mass Index; D005260:Female; D005355:Fibrosis / Q000150:complications*; D006509:Hepatitis B / Q000150:complications; D006526:Hepatitis C / Q000150:complications*; D006801:Humans; D008113:Liver Neoplasms / Q000453:epidemiology* / Q000209:etiology; D008297:Male; D009765:Obesity / Q000150:complications*; D011446:Prospective Studies; D012306:Risk; D012307:Risk Factors; D015430:Weight Gain