Obesity and Hepatocellular Carcinoma: Epidemiology and Mechanisms

The global epidemic of obesity posed a significant threat to healthcare systems because of the increasing incidence of its related comorbidities. In developed countries, lifestyle changes have promoted caloric excess and lack of physical activity. However, with increases in GDP, less developed countries, especially in Asia and the Middle East, are also noting an increase in obesity. Excessive fat deposition in obesity is widely accepted as a result of the disequilibrium between energy intake and expenditure. The prevalence of obesity has increased worldwide in the past 50 years and reached pandemic levels. There are more than 2 billion overweight or obese people worldwide. Obesity significantly increases the risk of many diseases including type 2 diabetes mellitus, nonalcoholic fatty liver disease, cardiovascular diseases, hypertension, myocardial infarction, stroke, musculoskeletal disease, osteoarthritis, and some types of cancer such as breast, colorectal, and liver cancer. In addition, obesity may cause unemployment, social disadvantages, and reduced socioeconomic productivity. Diet, physical activity, and lifestyle changes have been considered to be the cornerstone of obesity treatment. Obesity is associated with an increased prevalence of nonalcoholic fatty liver disease (NAFLD). NAFLD is the most common form of chronic liver disease that affects approximately 25% of the general population worldwide and is found in 85–98% of morbidly obese patients. Nonalcoholic steatohepatitis (NASH), a subtype of NAFLD, is characterized by lipid accumulation, hepatocyte death, inflammation, and fibrosis. NASH is a significant risk factor for the development of liver cirrhosis and hepatocellular carcinoma (HCC).