Regional and Sex Differences in the Mortality Risk Associated with Primary Liver Cancer in Obesity: A Systematic Review and Meta-Analysis.

Obesity has increasingly become a prominent public health problem. Although some studies have shown that obesity is associated with the risk for primary liver cancer (PLC)-related mortality, the regional and sex differences are not clear. The aim of this meta-analysis was to further elucidate the influence of obesity on PLC prognosis from multiple aspects.This study used a systematic literature search on PubMed, Embase, Cochrane Library, Web of Science, Sinomed, and CNKI for eligible studies evaluating the effects of obesity on the prognosis of PLC. Data on PLC-related mortality, all-cause mortality, or recurrence should be available to obtain, and studies providing regional, or sex specificity are of concern. Hazard ratios (HRs) and the corresponding 95% confidence intervals (CIs) were used to assess the pooled risk.Obesity is strongly associated with an increased risk for PLC-related mortality. A significant regional difference was observed (North America: HR, 1.57; 95% CI, 1.06-2.34; Europe: HR, 1.53; 95% CI, 1.08-2.16; Asia: HR, 1.05; 95% CI, 0.92-1.19; Oceania: HR, 1.13; 95% CI, 0.76-1.67). A stronger association between excess body mass index (BMI) and an increased risk for PLC-related mortality was demonstrated in men compared with women (men: HR, 1.87; 95% CI, 1.25-2.77; women: HR, 1.22; 95% CI, 1.00-1.47). No association was observed in the analysis between obesity and all-cause mortality and recurrence risk in PLC (all-cause mortality: HR, 1.01; 95% CI, 0.96-1.06; recurrence risk: HR, 1.00; 95% CI, 0.88-1.15).This study demonstrated a stronger association between obesity and PLC-related mortality in North America and Europe and among men.