As we know, liver cancer is the third most deadly malignant tumor in the world, and about 700,000 people die from liver cancer worldwide every year. China is the country with the highest prevalence and mortality rate of liver cancer in the world, accounting for more than half of the total number of liver cancer patients worldwide. Liver cancer is the second most common malignant tumor in China, because of its insidious onset, early stage may have no symptoms or symptoms are not obvious, cancer cells proliferate fast, often when diagnosed most patients have already reached the middle and late stage, which is very tricky to treat, so people also often call liver cancer as “the king of cancer”. What are the causes of liver cancer? The etiology and the exact molecular mechanism of liver cancer are not fully understood. Currently, it is believed that its development is a multifactorial and multi-step complex process, which is influenced by both environmental and genetic material. Epidemiological and experimental research data show that hepatitis B virus (HBV) and hepatitis C virus (HCV) infections, aflatoxin (which is often produced by aflatoxin contamination of cereals, corn, and peanuts), blue-green algae toxin-contaminated water, long-term alcohol abuse, cirrhosis, sex hormones, nitrosamines, and trace elements are all associated with liver cancer development. However, regardless of the carcinogenic factors, they all eventually lead to loss of control of cell division through excessive cell proliferation, and this change in cell behavior is associated with the activation of certain proto-oncogenes in the cells. Scientists have also demonstrated that there are multiple genes mutated in hepatocellular carcinoma that become oncogenes. Is liver cancer contagious? Many people want to know whether liver cancer is contagious or not. In fact, cancer patients are not infectious and will not transmit to others through breathing or contact. Even if cancer tissues are removed from cancer patients and directly planted on another person, they will not survive and grow, so liver cancer is not contagious. However, recent genetic epidemiological studies have concluded that liver cancer has a certain degree of family aggregation and is a multi-factorial inheritance pattern disease, which is likely to be related to genetic factors and the environment in which they live together. The high incidence of liver cancer in families may be related to the high chance of family members being exposed to the same risk factors. For example, mutual transmission of hepatitis B and C among family members or drinking from the same contaminated water source makes the development of liver cancer familially aggregated.