Impact of overweight and obesity on the risk of hepatocellular carcinoma: a prospective cohort study in 14.3 million Koreans

BackgroundWhether obesity and being overweight, defined by body mass index (BMI), increase hepatocellular carcinoma (HCC) has been less apparent in Asian populations.MethodsOverall, 14,265,822 Korean adults who underwent routine health examinations during 2003–2006 were followed up for HCC. Multivariable-adjusted hazard ratios (HRs) associated with BMI were calculated.ResultsDuring 13.7 years (mean) of follow-up, 47,308 individuals developed HCC. HRs of HCC associated with BMIs of 25.0–26.4, 26.5–27.9, 28.0–29.4, 29.5–30.9 and ≥31 kg/m² compared to those for 23.5–24.9 kg/m² were 1.05, 1.20, 1.39, 1.59 and 2.13, respectively. For BMI < 25 kg/m², linear associations were not apparent. For BMI ≥ 25 kg/m2, the HR per 5 kg/m2 increase in BMI was 1.60 (total), 1.60 (men), and 1.59 (women). The corresponding HRs were 1.56, 1.61 and 1.60 for individuals aged <45, 45–64 and ≥65 years, respectively. Further adjustment for alanine transaminase (ALT) levels substantially reduced the HRs for high BMI, especially in men and younger adults.ConclusionsOverweight and obesity clearly increase HCC risk in Koreans. ALT levels are a mediator of the impact of obesity, but it may not accurately predict high BMI-induced liver damage that can potentially progress to HCC, especially in women and older adults.