China is a country with a very high incidence of liver cancer. According to clinical research for many years, the following nine risk factors are the main causes of liver cancer.
I. Viral hepatitis
Among known hepatitis viruses, except hepatitis A virus, all of them are related to liver cancer, but the more researched and more consistent view is that hepatitis B virus (HBV) and hepatitis C virus are closely related to liver cancer. Persistent infection with hepatitis B virus and hepatitis C virus leads to chronic hepatitis and hepatic steatosis, and some patients develop liver cancer on this basis. Hepatitis B virus (HBV) is the leading cause in developing countries, while hepatitis C virus (HCV) is the leading cause in developed countries. Chronic HBV infection increases the risk of liver cancer by 200 times.
Second, eating food contaminated with Aspergillus flavus and its mycotoxins
Studies have found that there are more than 10 kinds of mycotoxins can induce tumors in different organs of animals. Aspergillus flavus is one of several toxic molds, its toxin B1 (aflatoxin B1, AFB1) has a strong toxicity to the liver. Numerous research studies have found that the distribution map of aflatoxin contamination is almost identical to the geographical distribution of areas with high incidence of liver cancer.
AFB1-containing food is ingested, by absorption to the liver, causing hepatocyte degeneration, necrosis, and then induce liver cancer. Aflatoxin has a strong hepatocarcinogenic effect, aflatoxin B1 on the rat liver cancer effect is 75 times stronger than dimethylnitrosamine. China’s high incidence of liver cancer by aflatoxin contaminated food fed to experimental animals, 6 months after the liver cancer induction rate of up to 80%. Aflatoxin B1 intake is positively correlated with the mortality rate of hepatocellular carcinoma. In addition, aflatoxin B1 and hepatitis B virus and synergistic hepatocarcinogenic effect. Foods susceptible to mold are rice, wheat, soybeans, peanuts, corn, canola oil, etc.
Third, drinking alcohol
Epidemiological survey shows that long-term heavy alcohol consumption is related to liver cancer. Alcohol consumption has a significant and independent effect on the occurrence of liver cancer, and there is a significant dose-effect relationship. It is generally believed that excessive alcohol consumption often leads to liver cancer through the steps of fatty liver, alcoholic hepatitis and liver steatosis. Hepatocellular carcinoma occurs in 10%-30% of alcoholic hepatic steatosis.
Most liver cancers in Europe and America are accompanied by alcoholic liver disease. Studies have shown that the risk of liver cancer is five times higher when drinking more than 80 g of alcohol per day for more than 10 years than when drinking less than 80 g of alcohol per day. Patients with hepatitis C who drink alcohol have two times the risk of liver cancer than those with hepatitis C alone.
Contamination of water source
Pollution of drinking water by certain chemical carcinogens and certain algae is also related to the occurrence of liver cancer. More than 100 kinds of carcinogenic or pro-carcinogenic substances have been found in polluted water.
Drinking water, especially ditch and pond water, is often contaminated by organic carcinogens (such as hexachlorobenzene, benzo(a)pyrene, PCBs, etc.). In Qidong, Jiangsu Province, a high incidence of liver cancer, the incidence of liver cancer among residents who drink ditch and pond water and those who drink well water is significantly different. There is a kind of blue-green algae in our ditch and pond water that can produce algae toxin – microcystin, which has been proved to be a strong cancer-promoting agent.
Chemical carcinogens
Some chemical substances such as nitrosamines, azo mustards, alcohol, organochlorine pesticides, etc. are carcinogens of liver cancer. Among them, N-nitroso compounds are the main ones, and dimethylnitrosamine and 3-nitroaniline are found to induce liver cancer in animal experiments.
Epidemiological surveys show that the risk of liver cancer is significantly higher in individuals with long-term exposure to pesticides or insecticides. Animal experiments have confirmed that some highly toxic pesticides such as pentachlor(benzene)phenol and hexachlorobenzene can induce liver cancer formation. China is a large agricultural country, people should pay attention when using organic solvents such as pesticides or insecticides.
Sixth, disease factors
It has been found that some diseases can increase the risk of liver cancer, such as diabetes, esophageal varices, cirrhosis, obesity, fatty liver, hereditary hemochromatosis, hereditary capillary dilation, α1-antitrypsin deficiency and so on. The mechanism of carcinogenesis by disease factors is still unclear.
VII. Genetic factors
Hepatocellular carcinoma has obvious family aggregation and genetic susceptibility. The number of hepatocellular carcinoma in families with blood relations far exceeds that of those without blood relations, and the number of close relatives is higher than that of distant relatives. The incidence of hepatocellular carcinoma in first-degree relatives is significantly higher than that in the control group (2 times).
VIII. Nutritional factors
Studies have found that vegetable and fruit intake can reduce the risk of cancer. It has also been found that drinking coffee is related to the reduced incidence of liver cancer, and there is a dose-effect relationship, and regular coffee consumption is a protective factor for liver cancer. Selenium is a cancer-inhibiting element, and selenium can improve the immune function and detoxification function of the body. The deficiency of selenium contributes to the formation of liver cancer. For example, seaweed is very rich in selenium.
IX. Immune status
It is believed that the plasma of liver cancer patients contains a kind of confinement factor, which can inhibit cellular immunity and protect liver cancer cells from being killed by immune cells. It has been proved that the AFP produced by liver cancer has this effect.
People with high risk of liver cancer need to have their liver function checked annually, and prevention of liver cancer should start from normal living habits, stay away from acquired cancer-causing factors and actively treat hepatitis to minimize the incidence of liver cancer.