Hepatocellular disease is the sixth most common cancer worldwide, with 841,080 new liver cancer cases and an estimated 1 million deaths in 2018. The incidence of HCC is increasing in different parts of the world, especially in East Asia and Africa. Hepatitis B virus (HBV) infection is the most common cause of HCC, with 50% of all HCC cases due to this viral disease. It is passed from mother to child during birth, through sexual contact, or by sharing needles that are used for injecting drugs. Routine hepatitis B vaccination in infancy is reducing the incidence of HBV infection.
Inflammation is a key factor in HCC development. It can lead to hepatocellular hyperplasia, cirrhosis and eventually hepatocellular carcinoma. Excessive alcohol consumption, nonalcoholic fatty liver disease (NAFLD), nonalcoholic steatohepatitis (NASH) and other chronic liver diseases are associated with inflammation, which leads to increased cancer risk. Other aetiological factors that contribute to the development of liver cancer include hepatitis viruses, hepatotoxins and genetic disorders.
A number of hepatotoxins, including aflatoxin B1 and alpha-galactosidase enzyme deficiency, can increase the risk of liver cancer. In addition, hepatitis C virus (HCV) infection and chronic hepatitis B virus (HBV) infections are also known to increase the risk of liver cancer.
The hepatotoxins inflict DNA damage and activate a series of oncogenic pathways that contribute to tumour growth, proliferation and a loss of hepatic function. These processes are mediated by transcription factors, such as p53 and NF-kB and induce oxidative stress and inflammation. In addition, these agents inhibit the anti-tumour activity of immune cytokines, such as IL-6 and TNF.
Vaccines are effective against both HCV and HBV, but they do not prevent or cure other hepatotoxins or genetic disorders that increase the risk of developing HCC. For example, cystic fibrosis, alpha-1 antitrypsin deficiency and hemochromatosis are inherited diseases that cause liver tissue to become overactive. Cystic fibrosis is also associated with obesity, alcoholic hepatitis, and NASH, which can also increase the risk of liver cancer.
Hepatotoxins are also associated with a variety of other disorders, such as diabetes and metabolic syndrome. In addition, certain foods, such as corn, nuts and milk, can contain aflatoxins that can cause liver damage and increase the risk of HCC.
The risk of developing liver cancer can be reduced by avoiding tobacco products, eating low-fat diets, exercising regularly and getting plenty of sleep. Several studies have shown that people who consume more than 30 grams of fat per day have a higher risk of developing liver cancer than those who eat less than 15 grams of fat a day.
Surgical resection of HCC is generally performed in the early stages. However, the recurrence rates are high and the overall survival is relatively short. Hence, it is important to screen for liver function, hepatitis markers and HCC at the earliest stage. Patients with hepatitis C or HBV infection, elevated bilirubin and portal hypertension should be evaluated for treatment options.
