At present, it is generally believed that the average annual chance (possibility, probability) of each person getting various malignant tumors is 180/100,000, which is 1.8/1000 (less than 2 per 1,000). A person suffering from tumor, just like a person committing a crime or a society becoming corrupt, is the result of multiple factors working together and interacting with each other through multiple pathways/mechanisms and going through multiple stages, and is never something that happens overnight. Philosophically, the occurrence of a thing is the result of the interaction of internal and external factors, following the universal law that external factors are the conditions for change, internal factors are the basis for change, and external factors act through internal factors. This is also true for the occurrence and development of tumor! The external factors leading to tumor (external factors), that is, the so-called environmental factors, are widely existed in people’s production and life process, very important but often easy to be ignored, mainly including: 1. physical factors: (1) ionizing radiation: X-ray examination (X-ray film, CT scan, etc.); cell phone, computer and other electronic products radiation pollution; luminous watches, glazed ceramics, 131I and other isotope pollution; mining (uranium ore, radon gas in mine); radon gas in the mine; radon gas in the mine. ); nuclear pollution (nuclear power plant accident). In addition, ultraviolet light is also a common factor (mainly from sunlight exposure). (2) Non-ionizing radiation: thermal radiation (hot bed, abdominal oven for heating in some rural areas in winter); (3) Long-term mechanical irritation: such as unsuitable teeth/denture trays (can lead to gum/cheek mucosa cancer); long-term non-healing ulcers; asbestos/glass fiber (lung cancer/pleural mesothelioma). 2., chemical factors: (1) polycyclic aromatic hydrocarbons: mostly found in coal tar, smoke (coal, gas/car exhaust/industrial exhaust), kitchen smoked and fried; (2) nitrosamines: mostly found in smoked and fried meat/salted fish; overnight vegetables, pickles; smoke; sauerkraut/dried potatoes; sausage/cheese/beer; cured fish; moldy food. (3) Aromatic amines / azo dyes: such as various coloring agents / herbicides / insecticides / antioxidants / synthetic dyes / industrial solvents / lubricants. Tobacco burning smoke contains more than 40 kinds of carcinogenic substances, which can not only cause cancer (lung cancer, oral cancer, esophagogastric cancer, breast cancer, bladder cancer, etc.), but also cause pharyngitis, bronchitis, promote atherosclerosis and ulcers and many other diseases. 3. Biological factors: Carcinogenesis is related to certain viral bacterial infections, but there is no report that cancer is contagious and can be transmitted. Burkitt’s lymphoma/leukemia/nasopharyngeal carcinoma and EBV, liver cancer and hepatitis B/hepatitis C virus (chronic hepatitis B – cirrhosis – liver cancer caused by hepatitis B virus infection is considered to be the “trilogy” of liver cancer development), human papillomavirus (HPV ) / herpesvirus II (HSV) and cervical cancer, HIV and Kaposi’s sarcoma / lymphoma / leukemia, H. pylori and gastric ulcer / gastric cancer (transmitted through kissing?). There are varying degrees of association. Aflatoxin produced by Aspergillus flavus (fungus) (widely found in aflatoxin-contaminated peanuts, peanut oil, corn, rice, cottonseed, pecans, dried peppers and other foods) can cause liver cancer in humans and many animals. And the internal factors refer to the internal factors of the body, such as genetics, nutrition, endocrine disorders, immune deficiency, mental tension, etc. 1. Genetic/family factors: the predisposition or susceptibility of a person to develop tumor. The so-called tumor heredity is not inherited from the tumor itself, what is inherited is a predisposition or susceptibility to develop tumor. On the basis of this, coupled with the effect of carcinogenic and cancer-promoting factors in the environment (exogenous factors), tumors can only arise through a complex cancer process. In fact, only a very few tumors have a clear genetic predisposition: retinoblastoma (nephroblastoma/neuroblastoma) and colonic polyp syndrome, which usually develop in adolescents and even in young children. Some common tumors (such as breast cancer, colon cancer, malignant black and lung cancer) only have a family susceptibility. For example, a person whose immediate new family members (such as parents, siblings) have one of these tumors has a 2-3 times higher chance of developing this tumor than the average person. But we don’t need to worry about this, because the probability of each person getting breast cancer or colon cancer or lung cancer is only about 40~50/100,000 per year, even if it increases by 2~3 times, it is still very low, moreover, even if your immediate family members have cancer (you were born in a family with tumor, or your family history of tumor is positive), you can still reduce the occurrence of tumor by avoiding or reducing the role of external factors. As the saying goes, “you can’t help yourself, but you can choose your own path”! 2, immunity: immunity is the body’s resistance to disease, human immune system is equivalent to the judicial police military system of society, and human tumor is equivalent to the corrupt black evil forces of society: (1) low immune function is prone to tumor development; (2) human tumor comes from the malignant change of human body’s own cells, the antigenicity is poor, the immune system can not find cancer cells “foreign”. (2) human tumor originates from the malignant change of human body cells, which is less antigenic and the immune system cannot detect the cancer cells “foreigners”, which is equivalent to the serious corruption and mutiny within the Communist Party in the whole society, with strong concealment and great danger; (3) tumor releases “closure factor” to paralyze the immune system and evade “immune surveillance”; (4) after the occurrence of tumor, the immune system will be paralyzed by the tumor. (4) Tumors are more likely to cause the decline of immune function after the occurrence of tumors. (3) Endocrine disorders: (1) Endometrial cancer is common in women who are obese, infertile and late menopausal. (2) Long-term oral/external application of estrogen induces breast cancer. 4. Age factor: After 45 years old is the high incidence stage of tumor. (1) The thymus gland (immune organ) gradually atrophies in the elderly, the organ gradually ages, and the cells are prone to mutation, (2) Age increases, exposure to carcinogenic factors increases, and carcinogens accumulate in the body. 5. Mental-psychological imbalance: According to dialectical materialism, matter determines consciousness, consciousness is rooted in matter, and consciousness reacts on matter, thus it can be seen that mental-psychological imbalance is an internal cause and a cancer promoter (not a carcinogen), and it is wrong to ignore or overemphasize its role. Psychosomatic factors can affect the development of tumor by acting on the nervous system, endocrine system and immune system. Under the long-term interaction of internal and external factors, some changes occur in the cells of the body, manifesting as incurable inflammatory diseases and excessive proliferation (i.e. precancerous lesions), some of which are reversible within a certain time and degree, i.e. they can be transformed to normal tissues, while the other part continues to develop malignantly and form malignant tumors. The process of tumor formation, just like a person’s criminal fall, is divided into three stages: initiation stage, promotion stage and development stage, which eventually form highly destructive and invasive tumors and often metastasize and spread to other parts, which seriously affects patients’ life and quality of life. The latest information shows that the top 10 malignant tumor incidence rates in China are (nationwide male and female combined): trachea/bronchus/lung cancer, gastric cancer, liver cancer, esophageal cancer, breast cancer, colon cancer, rectal cancer, bladder cancer, pancreatic cancer, and brain/nervous system tumors. However, after comparison and categorization, we can simply divide common tumors in China into respiratory system tumors, digestive system tumors, genitourinary system tumors (breast cancer, bladder cancer) and central nervous system tumors, so that it is easier to remember. For men, respiratory system (trachea/bronchus/lung cancer, which can be abbreviated as lung cancer) is the most common, and the rest are digestive system (stomach cancer, liver cancer, esophageal cancer, colon cancer, rectal cancer, the incidence rate decreases from top to bottom according to the anatomical part of digestive tract) and genitourinary system tumors (bladder cancer, prostate cancer) in order. For women, breast cancer is the first, and the rest are respiratory system, digestive system and genitourinary system tumors (cervical cancer, ovarian cancer, uterine body cancer) in descending order. Thus, it can be seen that tumors are not terrible and can be prevented. The prevention of tumor should start from oneself, from the side, from little by little, change the bad habits, avoid and reduce as much as possible the long-term stimulation of internal and external undesirable factors in the body, adhere to the correct lifestyle: such as quitting smoking and limiting alcohol, balanced diet, proper exercise, maintaining a healthy mind, etc.