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.
Conclusion: Excess weight increases PLC risk. For people with HCV infection or cirrhosis, risk increases are greater than for general population.