Liver cancer is a common cancer in China. According to census data, liver cancer has the third highest annual mortality rate after stomach cancer and lung cancer; and China accounts for 45% of the global new cases of liver cancer every year, making it the country with the most concentrated incidence of liver cancer in the world. Clinically, patients with liver cancer have a history of hepatitis – cirrhosis – liver cancer, which shows that hepatitis and liver cancer are extremely closely related. From the epidemiological point of view, countries or regions with high incidence of liver cancer are also areas with high incidence of hepatitis, and in the same region, people with hepatitis have a much higher risk of liver cancer than those without hepatitis. In particular, hepatitis B is most closely related to liver cancer, and those with hepatitis B surface antigen (HBsAg) positivity are significantly higher than those with HBsAg negativity among liver cancer patients. In hepatitis B-related hepatocellular carcinoma, hepatitis B virus genomic DNA is detected in 80% or more of tumor cells, and its DNA (especially the X region) and encoded proteins interfere with DNA replication in normal cells, inhibit oncogenes such as PTEN and activate oncogenes such as c-myc (the latter two are genes that regulate cell proliferation and development), cause abnormal differentiation and proliferation, and lead to hepatocellular carcinoma. Necrotic hepatocytes affected by hepatitis B virus occur and are susceptible to various oncogenic factors in the process of proliferation, which is another reason why hepatitis B virus causes liver cancer. Long-term chronic inflammation will cause liver fibrous tissue proliferation, and the massive proliferation of fibrous tissue will make the liver harden, which is what we call cirrhosis. When the liver itself cannot fully compensate for the function of cirrhosis, serious complications such as ascites and gastrointestinal bleeding can occur. Some patients with chronic hepatitis and cirrhosis eventually develop liver cancer.