How to prevent primary liver cancer? This can effectively prevent primary liver cancer

Actively preventing and treating viral hepatitis is of great significance to reducing the incidence of liver cancer. Injection of inactivated hepatitis B vaccine is not only effective in preventing and treating hepatitis, but will also play a certain role in preventing liver cancer. Avoid unnecessary blood transfusions and the use of blood products. Preventing food from going moldy, improving the quality of drinking water, and quitting drinking habits are also important measures to prevent liver cancer. While the primary prevention of liver cancer has not yet been perfected, early detection, early diagnosis, and early treatment of liver cancer, known as "secondary prevention" in oncology, are very important. Since the implementation of liver cancer screening, the diagnosis of primary liver cancer has entered the subclinical level, the proportion of early liver cancer has continued to increase, and the 5-year survival rate has also increased significantly. Since the 1980s, high-risk subjects for liver cancer (those over 35 years old with a history of chronic hepatitis or HBsAg positive) have been screened using AFp and ultrasound, and many early liver cancers have been detected. Early diagnosis and early treatment have effectively reduced the mortality rate of liver cancer.

1. Prevention among the crowd

Liver cancer is one of the most common malignant tumors in my country, with about 110,000 new cases each year, accounting for about 40% of the world's cases. Controlling the incidence of liver cancer and reducing mortality has been included in the prevention priorities of liver cancer in my country. Population prevention of liver cancer focuses on primary prevention and population census or screening.

The primary prevention of liver cancer is to prevent the occurrence of liver cancer, which is to make people avoid or minimize exposure to known carcinogenic factors and risk factors. According to the research on the etiology of liver cancer, my country has adopted the strategic measures of "controlling water, controlling food, and preventing hepatitis" in areas with high incidence of liver cancer, or implemented the primary prevention of "preventing and treating hepatitis, controlling food to prevent mold, supplementing selenium in moderation, and improving drinking water". The details are as follows:

(1) Water treatment and management, and improvement of drinking water hygiene: Organic pollution in drinking water is associated with liver cancer. Studies have shown that drinking highly polluted surface water, chlorinated water, and high-concentration chloroform water increases the risk of cancer. This risk may come from the multiple carcinogens in drinking water pollution that have additive and synergistic effects. Other studies have shown that drinking water and HBV carrier status have a significant synergistic effect on the development of liver cancer.

It has been found that drinking water in areas with a high incidence of liver cancer contains a variety of carcinogens. Although the content of each single carcinogen in these polluted water bodies is very small, the concentration of all carcinogens can reach the threshold of cancer after long-term and small-scale intake. Therefore, many scholars believe that water modification, water management, and improved drinking water hygiene may help reduce the incidence of liver cancer. In recent years, residents of Qidong County have strengthened drinking water management, and most residents have switched to drinking deep well water, which meets the health standards. Surveys show that the incidence of liver cancer has dropped significantly. Fusui County has combined agricultural water conservancy construction to improve drinking water on a large scale throughout the county, and most residents drink deep well water and water conservancy water, which has achieved good results.

(2) Strengthen anti-mold and detoxification of grain and oil products: Reduce the intake of aflatoxins and block or inhibit the carcinogenic effect of aflatoxins. In areas with a high incidence of liver cancer, the incidence of liver cancer is positively correlated with grain mildew, especially aflatoxin contamination of corn. Given that grain mildew mainly occurs during the field harvest period, the post-harvest processing period, and the storage period, many scholars believe that it is extremely important to strengthen anti-mold measures in these links. In addition, changing planting habits, replacing corn with rice, and promoting the consumption of rice are also ways to reduce the intake of aflatoxins.

For grain and oil foods that have become moldy but cannot be discarded, the mold particles can be selected and processed to remove certain toxins.

(3) Block HBV infection and actively prevent and treat hepatitis: Hepatitis B virus infection is currently a serious public health problem. In areas with a high incidence of liver cancer, the rate of hepatitis B virus carriers is also high. 80% of liver cancer patients are infected with hepatitis B virus. In liver cancer patients, hepatitis B virus DNA has been found to be integrated into the DNA of liver cells. Therefore, blocking HBV infection is an important way to prevent primary liver cancer, and vaccination with hepatitis B vaccine is the most fundamental and effective measure to control hepatitis B. WHO points out that vaccines should be used selectively in areas with low HBV prevalence. In areas with medium and high prevalence, all infants should be vaccinated, and the use of hepatitis B vaccine should be included in the expanded immunization program. Practice has shown that hepatitis B vaccination of newborns, especially newborns of HBsAg-positive and (or) HBeAg-positive mothers, has a reliable immune effect. In Qidong City, by the end of 1990, 41,717 newborns had been vaccinated, with a vaccination rate of 98.6%. The anti-HBS positive rate at the age of 5 reached 82%, and a downward trend in chronic hepatitis has been observed. The long-term effect of hepatitis B vaccination in preventing liver cancer needs further observation and confirmation.

(4) Drug prevention for people at high risk of liver cancer: Domestic and foreign studies suggest that increasing selenium levels may help reduce the incidence of liver cancer. New Zealand used sodium selenite granules to fertilize fields on low-selenium farms and Denmark sprayed selenium fertilizer on the land, which changed the local selenium deficiency phenomenon. Qidong County, my country, conducted a preventive trial on 380,000 people in a low-selenium area. By spraying selenium fertilizer on crops, the selenium levels of corn and barley increased by 6 times, and the blood selenium levels of residents also increased significantly. Animal experiments suggest that selenium can significantly inhibit hepatitis and precancerous lesions. The anti-cancer effect of selenium is mainly manifested in inhibiting the formation of hyperplastic foci in the early stage and inhibiting the canceration of hyperplastic foci in the late stage. A recent intervention experiment conducted by Sino-US cooperation on the site of residents in Qidong County showed that after taking selenium salt (15 mg/kg) and selenium yeast preparations for 4 years, the standardized incidence of liver cancer in the population dropped from 42/100,000 to 30/100,000, while the incidence in the control group did not decrease, and the difference between the two was significant. Practice has proved that selenium supplementation is safe and feasible in areas with high incidence of liver cancer. This shows the value and significance of selenium in preventing liver cancer.

Other chemical drugs reported at home and abroad that have preventive effects on liver cancer include levamisole, vitamin A and vitamin C. my country is rich in traditional Chinese medicine and natural food, and it is worth exploring the development of this treasure trove to prevent liver cancer. Recently, green tea has been studied more. Studies have shown that green tea has a significant inhibitory effect on rat liver cancer caused by aflatoxin B1. It has also been observed that green tea extract can inhibit diethylnitrosamine-induced rat liver cancer pre-lesions. Epidemiology in areas with a high incidence of liver cancer also suggests that green tea may have a certain preventive effect. In addition, some traditional Chinese medicines for the treatment of hepatitis, such as salvia miltiorrhiza, schisandra chinensis, shiitake polysaccharides, and versicolor polysaccharides, have been found to antagonize the formation of rat liver cancer caused by aflatoxin.

(5) Health publicity and education and implementation of relevant administrative regulations: Primary prevention is a social work aimed at a large population. It has a wide scope, high costs, and great resistance. It is difficult to show results in the short term and is difficult to implement. Therefore, it is important to implement health publicity and education in a planned, organized, and targeted manner to increase public awareness of cancer prevention. This is an important condition for ensuring the implementation of primary prevention measures for liver cancer. Relevant administrative measures and regulations should be adopted when necessary.

Primary prevention of liver cancer is important and has great potential in reducing liver cancer, but currently we should still emphasize the effective secondary prevention. In population prevention, implementing liver cancer screening and early detection of liver cancer is an important aspect of secondary prevention.

① Objects of the census: Before the 1980s, there was a big contradiction in the liver cancer census in my country, that is, the contradiction between "cost and benefit". The detection rate of the census in the natural population, even in a high-incidence area of ​​liver cancer such as Shanghai, was only 14.7/100,000, which was very costly and ineffective. Since the 1980s, based on the results of epidemiological surveys, the high-risk population for liver cancer has been divided. Therefore, the liver cancer census has shifted from the census of the natural population to the census of the high-risk population, and the detection rate has been greatly improved, which has well solved the contradiction between cost and benefit. This concept is also accepted by the majority of medical workers. It is generally believed that the high-risk population refers to those over 40 years old, those who are positive for hepatitis B surface antigen and have a history of chronic hepatitis for more than 5 years (referring to those who have had hepatitis 5 years ago), especially men and those with a family history.

② Method of census: A large-scale population census must adopt a simple, highly sensitive, accurate and reliable detection method. The hemagglutination method of alpha-fetoprotein (AFp) roughly meets this requirement. The lower limit of AFp hemagglutination is 40 μg/L, and its false positive rate is 30%. Every case of AFp hemagglutination positive should be reviewed by radioimmunoassay. Those whose AFp is indeed elevated should be recommended to see a specialist for examination.

The positive rate of AFp detection in patients with primary liver cancer in my country is about 70%, which means that nearly 1/3 of patients are difficult to detect early with AFp detection. Other liver cancer markers other than AFp are not suitable for general screening for various reasons. The clinical application of B-ultrasound has been proven to be a simple, accurate and reliable imaging diagnosis method, and has been gradually included in liver cancer general screening in recent years. The combined detection of B-ultrasound and AFp has indeed solved the problem of early detection of liver cancer in AFp-negative cases.

③ Interval between censuses: Regarding the interval between censuses, the reports of various scholars are basically consistent. It is generally believed that for high-risk groups, a census should be conducted at least once every 6 months.

④ Organization of the survey: Cancer prevention and treatment knowledge and the importance of early detection of cancer should be widely publicized through various channels. Special attention should be paid to the publicity work for high-risk groups so that they can take it seriously, undergo regular examinations, and avoid unnecessary tension.

To do a good job in the survey, it is necessary to mobilize the enthusiasm of medical personnel in grassroots health care organizations such as factories and mines, do a good job in mobilizing and organizing the subjects for inspection, and regularly inspect cases with increased AFp and supervise close follow-up.

Comprehensive prevention in areas with high incidence of liver cancer

Qidong City, Jiangsu Province: Comprehensive prevention of liver cancer: Since the 1970s, Qidong City, Jiangsu Province has started to prevent and treat liver cancer, and has done "water management, food management, and hepatitis prevention and treatment" in terms of prevention. The drinking water habits of Qidong residents have changed greatly. Basically, they no longer drink ditch water, well water, or river water, but mainly use deep well water (about 200 meters underground). Almost all the house ditches have been filled. By 1998, there were 263 deep wells, benefiting 1.133 million people, with a coverage rate of 96.8%. A high proportion of urban residents drink clean water. Drinking water pollution has been more thoroughly controlled. Aflatoxin (AFT) is one of the important factors for the high incidence of liver cancer in Qidong. In the past 20 years, the main measures have been to prevent mold and remove toxins, and reduce toxin intake. With the change of the staple food structure (from corn to rice), the intake of AFT has been relatively reduced. However, there are still a few residents who use corn as their staple food, and AFB1 has been detected in their corn samples, and serum AFB1 albumin adducts have been detected in their blood samples. The Qidong Liver Cancer Research Institute has also studied the use of chemical preventive agents to prevent and treat the hazards of AFT. Over the past 20 years, measures have also been taken to control the spread of hepatitis. From 1980 to 1999, the rate of increase in liver cancer mortality in Qidong slowed down. From 1975 to 1992, the liver cancer mortality rate increased by 1.99 times. This shows that comprehensive prevention has played a certain role.

Prevention of liver cancer in Fusui County, Guangxi Province: Since 1974, research on the prevention and treatment of liver cancer has been started. The main risk factors for the high incidence of liver cancer in Fusui County are aflatoxin, hepatitis B virus and drinking water pollution. In the past 20 years, comprehensive prevention of liver cancer for the whole population has been carried out with the main content of "reducing aflatoxin intake and improving drinking water", and chemical prevention has been tried in the high-risk population of liver cancer, which has achieved initial results. Since 1982, a systematic water improvement project has been implemented. The proportion of people drinking pond water in the county has dropped from 34% in 1981 to 9.4% in 1994. The proportion of residents drinking deep well water and tap water has increased from 22.5% to 63.6%. The incidence rate has decreased for those who have changed their water for 5 years, and the incidence rate has decreased significantly for those who have changed their water for 8 years. The incidence rate has dropped from 78.52/100,000 before the water improvement to 48.26/100,000 after the water improvement. The main measures to reduce the intake of aflatoxin include: changing the structure of staple food and reducing the proportion of corn in the ration. The proportion of corn in the ration has dropped from 40% in the 1960s to about 13% in the 1980s. Implementing measures to prevent mildew and detoxify grains and oils, the AFB1 positive rate of the samples tested dropped from 70.13% to 32.94% from 1972 to 1981 compared with 1982 to 1991, and the residents' AFB1 intake has been greatly reduced. Among the high-risk groups, levamisole, green tea and salvia miltiorrhiza have been used for chemical prevention, all of which have a certain effect. The incidence of liver cancer in Fusui has dropped by 24.94% from 1994 to 1974. Among them, the decline in the incidence of liver cancer in women is extremely significant. In the last ten years, the decline in the incidence of liver cancer in the 15-30 age group was particularly prominent, with a decline of 35.16% to 60.72% respectively. It is of particular significance in the current situation where the incidence of liver cancer is generally rising in many countries and regions at home and abroad.

2. Personal prevention

(1) Primary prevention: Personal primary prevention should be carried out on the basis of population prevention. In addition to consciously accepting various measures for population prevention, appropriate measures should be taken against pathogenic factors.

(2) Secondary prevention: Secondary prevention of liver cancer is early detection, early diagnosis, and early treatment, that is, preventing the clinical onset of liver cancer. For people at high risk of liver cancer, regular AFp and B-ultrasound examinations should be performed, at least once every six months, so that many liver cancer patients can be diagnosed early. The purpose of early diagnosis is early treatment. Early liver cancer should be surgically removed as much as possible to achieve a radical cure. Some scholars point out that the purpose of secondary prevention of liver cancer is to save the patient's life, and should not be satisfied with the extension of survival after diagnosis, because this extension of survival includes a period of survival brought about by early detection before clinical symptoms appear.

(3) Tertiary prevention: In addition to early detection for radical surgery, due to the progress of liver cancer surgery, secondary surgery for recurrent liver cancer and secondary surgery after "large liver cancer turns into small liver cancer" have enabled a large number of patients to be cured. For patients who have undergone radical surgery, regular and close follow-up should still be carried out, with AFp and B-ultrasound rechecked every 1 to 3 months. Early detection of recurrent liver cancer can be accompanied by taking drugs to protect the liver and enhance the body's immunity to prevent liver cancer recurrence. For patients who have undergone palliative treatment, a series of comprehensive measures such as hepatic artery catheterization embolization chemotherapy, local alcohol injection, radiotherapy, immunotherapy, and traditional Chinese medicine treatment should be adopted to prolong the patient's life span, improve the quality of life, and provide symptomatic treatment for the symptoms of late-stage liver cancer to relieve the patient's pain.