Malignant tumor, that is, cancer, is a new organism formed by normal cells in the human body becoming cancerous under the action of various carcinogenic factors, making normal cells become malignant cancer cells and abnormal proliferation of local tissues. It has become one of the most serious diseases threatening human health. According to 1980, there are 16 kinds of common cancers in the world. According to statistics, the number of cases is 6.35 million every year, of which China estimates that it is10 million, and the number of people who die of cancer reaches 800,000 every year, that is, 2,000 people die of cancer every day on average. In addition, malignant tumors cause a lot of labor losses and high medical expenses. For example, in the United States, only 1.990, the cost of cancer treatment reached1.04 billion US dollars, which caused a large consumption of social materials and brought immeasurable mental losses to patients and families. Therefore, malignant tumor has become a major concern of all mankind.
To prevent and control the harm of malignant tumor, we should first study the distribution law of malignant tumor in the population and the main factors affecting the distribution characteristics, and then explore its causes, formulate and evaluate the preventive countermeasures of malignant tumor, so as to achieve the purpose of preventing and controlling malignant tumor.
(1) Epidemiological characteristics of malignant tumors Since the 1920s, the incidence and mortality of malignant tumors have increased year by year.
1) There are differences in geographical distribution in different countries and regions, and the same malignant tumor also has different distributions in different regions. For example, liver cancer is common in Europe and America, and it has a high incidence rate in Japan, Malaysia, Indonesia, Singapore, China coastal areas and Zhuge Liang province south of the Yangtze River. The incidence of gastric cancer is relatively high in Japan, Chile, Finland, Austria, Iceland, Hexi Corridor in Gansu, Jiaodong Peninsula and coastal areas of Jiangsu and Zhejiang. Esophageal cancer is more common in northeast Iran, South Africa, Kenya and other countries. In China, Henan, Shanxi, Hebei and Beijing are high-incidence areas, with Taihang Mountain as the center and gradually decreasing around. The incidence of intestinal cancer in China is also increasing year by year, with Jiangnan higher than North China. The incidence of nasopharyngeal carcinoma is higher in Southeast Asia and South China (Guangdong, Guangxi, Yunnan, Jiangxi and Hubei), and the incidence of nasopharyngeal carcinoma in overseas Chinese is higher than that in local people.
2) From the perspective of urban and rural distribution, lung cancer ranks first in cities and gastric cancer ranks first in rural areas. The mortality rate of colon, rectum and anal cancer in urban population is significantly higher than that in rural areas, while the mortality rate of cervical cancer is significantly higher than that in urban areas.
3) According to the characteristics of population distribution, the incidence of tumor is different among different age, sex, race, occupation and immigrant population. Malignant tumors can occur at any age, but the incidence increases with age. The most common children are leukemia, brain tumor and malignant lymphoma. Liver cancer and leukemia are common among young people; Gastric cancer, esophageal cancer, cervical cancer and lung cancer are the main diseases of middle-aged and elderly people. The sex distribution of malignant tumors is more in men than in women, about 1.99: 1. Only gallbladder, thyroid, breast and reproductive tract tumors are higher in women than in men. Occupational bladder cancer mainly occurs in rubber and cable manufacturing industries, and occupational lung cancer mainly comes into contact with asbestos, arsenic, chromium, nickel and radioactive mine mining industries. The racial differences of malignant tumors are very obvious, and nasopharyngeal carcinoma is more common among Cantonese in China. Atomic liver cancer is more common in Africans, oral cancer is more common in Indians, esophageal cancer is more common in Kazakhs, and cervical cancer is less common in Israeli Jews.
(2) Main risk factors of malignant tumor The risk factors of malignant tumor can be divided into six categories: behavior and lifestyle, environmental physical and chemical factors, social and psychological factors, drug factors and virus factors.
1) Behavior and lifestyle Smoking is related to the incidence of various cancers, among which lung cancer is the most closely related. Smoking can increase the death rate of lung cancer by more than 10 times, and the earlier you smoke, the more you smoke, and the greater the risk of lung cancer. Smoking not only causes lung cancer, but also causes many cancers such as oral cavity, pharynx, larynx, esophagus, pancreas and bladder.
Drinking alcohol is related to oral cancer, pharyngeal cancer, laryngeal cancer and rectal cancer. Long-term drinking can lead to cirrhosis, which may be related to liver cancer. Drinking and smoking will increase the risk of some malignant tumors.
Pickled food and pickles are risk factors for gastric cancer; Sodium nitrite is a preservative, which reacts with amines in acidic environment (PH3.0) to generate nitrosamines, which are carcinogens. Aspergillus flavus pollutes rice, wheat, corn, peanuts and soybeans to produce aflatoxin, which has carcinogenic effect; Smoked sausages, leg inflammation and other smoked foods may contain carcinogen benzopyrene. Rough food, long-term iron deficiency, malnutrition, increased risk of esophageal cancer and gastric cancer. Low sun concentration in diet and low blood selenium level are prone to malignant tumors.
2) Environmental physicochemical factors According to the statistics of the World Health Organization, 80%-90% of human malignant tumors are related to environmental factors, the most important of which is environmental chemical factors. At present, it has been proved that there are more than 100 species that can cause cancer in animals, and more than 30 species that can cause cancer in humans. Urban air pollutant benzopyrene is closely related to lung cancer, and about 10% of lung cancer cases are caused by air pollution (including the combined effect with smoking).
Ionizing radiation can cause a variety of human cancers, such as acute and chronic myeloid leukemia, multiple myeloma, malignant lymphoma, lung cancer, thyroid cancer, breast cancer, gastric cancer, liver cancer and so on.
3) Unique emotional life history and social psychological factors can lead to the occurrence of cancer. Unfortunate family events, excessive work and study pressure, uncoordinated interpersonal relationships, early death and divorce of parents in childhood, frustration in adulthood, widowhood, career failure, sadness and despair caused by continuous pressure, etc., are all important social and psychological factors leading to cancer.
Individual personality characteristics are also related to malignant tumors: ① sentimentality and depression; (2) impatient, forbearing, unsociable, taciturn and indifferent to things; 3 withdrawn and eccentric; Long-term loneliness, contradiction, disappointment and depression are important factors to promote the growth of malignant tumors. Some people call this personality "cancer personality".
4) Drug factors At present, it has been proved that many drugs can induce malignant tumors. For example, long-term use of estrogen can lead to vagina and cervical cancer, and arsenic can lead to skin cancer. Excessive exposure or acceptance of radionuclides, drugs iodine and phosphorus can cause acute myeloid leukemia, and long-term use of phenacetin can induce pyelonephritis. Chloramphenicol can lead to aplastic anemia, which is also the prophase of leukemia. Although cyclophosphamide can treat cancer, it can also induce leukemia, breast cancer and bladder cancer.
5) Occupational factors Occupational-related risk factors include physical factors such as ionizing radiation, ultraviolet rays and exposure to various chemical carcinogens. Common confirmed occupational carcinogens can be found in Chapter 5 "Occupational Diseases".
6) Viral factors At present, it is believed that hepatitis B virus (primary liver cancer), EB virus (lymphoma, nasopharyngeal carcinoma) and herpes simplex virus II (cervical cancer) may be closely related to human tumors.
(3) Prevention of Malignant Tumors Preventive measures for malignant tumors are mainly primary and secondary prevention.
1) Primary prevention ① Strengthen cancer prevention health education: especially for high-risk groups, to improve their awareness of prevention and self-care ability, they are required to strengthen their physical and mental cultivation, improve their psychological quality, treat life correctly, treat setbacks, maintain a good healthy psychological state, pay attention to a balanced diet and nutrition, do not eat the same diet repeatedly, do not take the same medicine for a long time, do not smoke, and avoid excessive drinking. Eat foods rich in vitamins A, C, E and dietary fiber in moderation, eat less salty, overheated and burnt foods, avoid moldy foods, avoid excessive sun exposure and overwork, maintain personal cleanliness, pay attention to physical exercise, enhance physical fitness and improve anti-cancer ability; (2) Rational use of medical supplies, no abuse of drugs and radiation, especially diagnostic radiation of pregnant women, to prevent the occurrence of leukemia, osteosarcoma and skin cancer. ; ③ Eliminate occupational carcinogens, especially strengthen the detection, control and elimination of confirmed carcinogens to prevent the occurrence of occupational tumors; ④ Strengthen labor protection, environmental protection and food hygiene to reduce or eliminate carcinogenic factors in the environment.
2) secondary prevention ① asymptomatic crowd monitoring: breast cancer monitoring: women over 30 years old should undergo breast self-examination (Figure 86), women over 40 years old should undergo 1 time clinical examination every year, and women over 50 years old should undergo clinical and necessary X-ray screening every year. The high-risk groups of breast cancer include menarche before the first pregnancy, menopause, obesity after 50 years old and high-fat diet. ② Monitoring of cervical cancer: All women who have sexual life are at risk of cervical cancer, and cervical exfoliated cells 1 smear should be checked every 2-3 years from sexual life; ③ Monitoring of colorectal cancer: 1 rectal finger examination should be performed every year for people over 40 years old, and 1 fecal occult blood examination should be performed every year for people over 50 years old, especially those with family history of tumor, polyp, polyp ulcer and colorectal cancer; Do 1 colonoscopy every 3-5 years.
Monitoring of people with symptoms: As more than 75% of malignant tumors in human body occur in places that are easy to find and find, paying attention to the cancer signals of common malignant tumors (see Chapter 5, Section 29 for details) and taking the initiative to go to the hospital for examination in time are conducive to early detection, early diagnosis and early treatment of malignant tumors.