Hepatitis B does not have the statement of how many years old it is easy to become cancerous, but about 5% of the population will be transformed from hepatitis B to liver cancer, usually after 20 to 30 years of having hepatitis B. Hepatitis B is an infectious disease caused by the hepatitis B virus, which manifests symptoms such as pain in the liver area and fatigue, and is clinically diagnosed by testing for hepatitis B surface antigen and other indicators, and hepatitis B surface antibodies can be produced through hepatitis B vaccination, which protects the human body from infection by the hepatitis B virus. Hepatitis B can cause hepatitis, cirrhosis, liver fibrosis and other diseases, if you fail to timely control and treatment of hepatitis B virus infection, cirrhosis, liver fibrosis after a long period of time continues to aggravate, it will lead to cancerous liver cells, about 5% of the patients have a probability of hepatitis B will be transformed from hepatocellular carcinoma after 20 to 30 years. Hepatitis B does not change into liver cancer at a fixed age, but about 5% of the population will change from hepatitis B to liver cancer, usually after 20~30 years of having hepatitis B. If the condition of hepatitis B is not controlled in time, the cancer may occur more quickly.