The causes of tumor development are still under in-depth research, but a large number of clinical observations and experimental research data show that many factors have a close relationship with the development of malignant tumors. Modern medical research has confirmed from epidemiological survey and experimental research data that the etiology of tumor can be divided into the following aspects: external factors of tumor development (including chemical, physical and biological carcinogenic factors), internal factors of tumor development (including immune function, endocrine, genetic and mental factors, etc.), as well as dietary and nutritional disorders and poor living habits, etc. External factors of tumor development (a) Chemical carcinogenic factors At present, chemical carcinogenic factors are the main causes of tumors, and their sources are very wide and diverse. It has been confirmed by investigation and animal experiments that there are more than a thousand kinds of chemical substances with carcinogenic effects, among which there are hundreds of chemical carcinogens closely related to human beings. Chemical carcinogenic latency period is relatively long and extremely harmful to human beings, it is widely present in food, production and living environment, pesticides, medical drugs. The well-known aflatoxin, contaminated in peanuts, corn, sorghum, rice and many other food crops, has a recognized carcinogenic effect, has obvious carcinogenic power, and has been proven to cause liver cancer. The types and contents of carcinogens in naturally widespread nitrosamines (higher in cured fish, meat and chicken) and smoked or burnt foods (especially high-protein foods such as fish, meat and eggs) increase dramatically, as well as air contaminated with carcinogens such as polycyclic aromatic hydrocarbons (PAHs), such as 3,4 benzo(a)pyrene, dimethylbenzene(a)pyrene and dibenzopyrene, can affect the human body and, in serious cases, can induce and They can lead to lung cancer, nasopharyngeal cancer, esophageal cancer, cardia cancer, stomach cancer, liver cancer, leukemia, bladder cancer, colon cancer, scrotum cancer, skin cancer, etc. (ii) Physical carcinogenic factors Physical carcinogenic factors include burning, mechanical stimulation, trauma, ultraviolet light, radiation, and so on. It is worth paying high attention to the fact that the harm by radiation can come from environmental pollution or from medical source. For example, repeated X-ray irradiation examination or radionuclide examination can increase the chance of tumors in the examined population, and if certain diseases are treated with radiation therapy, certain tumors can be induced. Some data reported that after treating erythrocytosis with radionuclide phosphorus, a significant number of patients developed leukemia after a certain latency period. Repeated chest radiographs in patients with tuberculosis can induce breast cancer. (iii) Biological carcinogenic factors At present, more research on such factors are viruses. Recent scientific research has proved that more than 30 kinds of animal tumors are caused by viruses. Recently, it has been found that some human tumors are closely related to viruses, and antibodies to the corresponding viruses can be found in the sera of some patients with nasopharyngeal cancer, cervical cancer, liver cancer and leukemia. Some information reported that schistosomiasis can induce colorectal cancer and liver cancer, etc. When its function is normal, it can effectively resist and destroy the invading bacteria and viruses, and remove the foreign toxic substances and metabolites in the body. The immune function of the body plays an important role in the occurrence and development of tumor. Clinical research data proves that human body does have immunity to tumor, and many patients can survive with tumor for a long time without deterioration, which shows that the body has certain resistance to tumor, which is what Nei Jing says: “If the righteousness exists inside, evil cannot dry up”. When the immune function of the body is suppressed or damaged, the incidence of tumor is high, the growth is fast, and it is easy to metastasize. According to traditional Chinese medicine, the formation of tumor is related to the deficiency of righteousness; it is clearly stated in The Essential Reading of Medicine: “The formation of tumor is due to the deficiency of righteousness and then the entrenchment of evil.” (2) Effects of endocrine disorders Endocrine disorders have a certain role in the occurrence and development of certain tumors. Clinical observation data show that some long-term users of male enesthene induced breast cancer; some female breast cancer patients (under 60 years old) treated with male hormones, or treated with estrogen (over 60 years old), can reduce symptoms. It has been found that endocrine disorders are related to the occurrence of thyroid cancer, breast cancer, cervical cancer, ovarian cancer, etc. (iii) Influence of genetic factors The issue of direct influence of genetic factors on human tumors has yet to be studied in depth. So far, among human tumors, only retinoblastoma, nephroblastoma, neurofibroma and colonic polyp syndrome are considered to have obvious genetic predisposition. Some scholars have reported that breast cancer, the most common type of cancer in European and American women, has a hereditary predisposition in about 30% of cases; certain digestive tract cancers (such as gastric cancer, esophageal cancer and liver cancer) also have hereditary predisposition; lung cancer also seems to have a certain hereditary predisposition. It has been reported that foreign scholars have shown after more than 20 years of research that cancer can be hereditary. In their experimental research, they found that the “P53 gene”, which is closely related to cancer, has the function of inhibiting abnormal cell division (i.e. cancer suppression) when it is functioning normally, but when it is mutated and out of order, the cells can easily become cancerous due to the lack of a containment factor. At present, dozens of cancer patients have been found to have mutations in this gene, and it is believed that P553 gene is related to 80% of human cancers. (4) Influence of mental factors Mental factors, i.e. happiness, anger, sadness, thought, grief, fear and fright, as outlined by Chinese medicine, have an important influence on the immunity of patients against cancer. According to the “Good Formula for Women”, the occurrence of “breast rock” is “due to depression and anger in the liver and spleen, and loss of qi and blood”. Many clinical studies have shown that emotional well-being has a significant relationship with the occurrence of cancer. Most cancer patients have major trauma, or have long time mental depression, depression, etc. People with cheerful personality rarely suffer from cancer. Diet and nutrition are necessary for human survival and health, but diet should be controlled and nutrition should be sufficient, otherwise it will affect the normal function of human body and lead to disorder of qi or damage of positive qi and produce diseases. Ancestral medicine has long recognized that dietary strain can lead to the occurrence of tumors. If the diet is thick and spicy, it affects the function of the spleen and stomach, the spleen is the main dampness, the spleen is weak and cannot transport water and dampness, the dampness is contained in the interior, the accumulation is not dispersed, the fluid is not transformed, the fluid coalesces into phlegm, the phlegm accumulates and becomes swelling. Jing Yue Quan Shu Dysentery on accumulation of dirt” is very clear: “The stagnation of food and drink, stay stored in the middle, or agglomerate into lumps, or fullness, hard and painful, does not change, some blockage, is the accumulation.” There is also an insightful discussion in the “Ji Sheng Fang”: “over meal five flavors, fish and fishy cheese, strong food raw and cold fruits and vegetables, stagnation of the stomach and epigastric, …… for a long time is the accumulation of obstruction.” This is consistent with the view that nutritional disorders are related to the occurrence of tumors in recent medical research. The scholars at home and abroad have reported that drinking tea can destroy the human esophagus “mucosal barrier”, from the medical point of view, where fast, coarse, hot, spicy, heavy diet is harmful to the esophagus. Experts believe that drinking boiling porridge, boiling soup and boiling tea is prone to esophageal cancer. The epidemiological survey in China’s esophageal cancer-prone areas also shows that the development of esophageal cancer is related to dietary habits, such as high-heat diet, rough food, hard and difficult texture, swallowing too fast, etc., which can cause damage to the esophageal mucosa, coupled with the role of infection and other factors, so that the inflammation of esophagus will not be cured for a long time, leading to the occurrence of cancer. Bad habits include partial diet, smoking, alcoholism, unscientific cooking and so on. Modern medical research confirms that bad habits are the biggest hazard leading to cancer. This has been recorded in Chinese medical texts, “Medical History of Regurgitation and Choking” said that the cause of choking (i.e. modern medicine named esophageal cancer or pancreatic cancer, etc.) is “drinkers often choke and diarrhea, especially those who drink hot wine, to heat injury fluid, the throat is dry, food can not enter. Han Yu, a great literary scholar of the Tang Dynasty, said, “The only thing that breaks off life is wine”, which is very philosophical. At present, smoking has become a worldwide social nuisance, seriously threatening human health. According to the World Health Organization (WHO) experts predict that in 1994, the number of deaths caused by smoking around the world has reached more than 3 million, it is estimated that by 2025 the number of deaths caused by smoking will increase to 10 million. The amount of smoking in China is increasing year by year, and the history of smoking is getting longer. Sixty percent of adult males in China have a history of smoking, and it is estimated that the number of people harmed by smoking is more than 600 million. According to a recent study by the Chinese Academy of Preventive Medicine, China’s annual economic loss caused by smoking has exceeded 30 billion yuan, died of smoking-related diseases more than 1.2 million people, of which a high proportion of cancer deaths. Our oncologists believe that there are six main risk factors for malignant tumors, the first being smoking. Smoking causes a high relative risk of squamous cell lung cancer, and smoking is associated with 1/3 of cancers. A comprehensive study reported that the cancer incidence of smokers in the United States, the United Kingdom, and Canada are: lung cancer deaths are 108 times more common among non-smokers; laryngeal cancer deaths are 54 times more common among non-smokers; oral cancer and pharyngeal cancer deaths are 41 times more common among non-smokers; esophageal cancer is 34 times more common among non-smokers; and bladder cancer is 19 times more common among non-smokers. Some scholars have called for a dramatic increase in the number of Chinese men dying from lung cancer due to heavy smoking, and by the next century, 2 million people will die from smoking, half of whom will die from lung cancer. According to the report of the American Cancer Authority, poor dietary habits account for 35% of cancer-causing factors, smoking accounts for 30% of cancer-causing factors, and the two together account for 65%. In view of this, it is very important to pay attention to the above controllable aspects of prevention, so that the vast majority of people can stay away from tumors, and everyone starts from themselves.