Not long ago, the Beijing Municipal Bureau of Health announced the list of causes of death of the city’s residents in 2007. The data show that malignant tumors, from the third cause of death in 2006, jumped to the first place, more than two or three cerebrovascular disease and heart disease, for the first time to cause the death of Beijing residents, “the first killer”. Until now, the specific cause of malignant tumors is not clear, and its mechanism can only be some assumptions, the most classic theory is the two strikes doctrine: after birth, there are genetic defects, which is the first strike; and acquired environment, diet, mental stress, etc. on the role of defective genes, the formation of the second strike. The two strikes, eventually lead to malignant tumors. Elderly people are more prone to malignant tumors, which is related to their decreased immunity. In fact, there are tumor cells in everyone’s body, except that the immune system is able to detect the tumor cells in time and get rid of them. When a person gets older, the ability of immune surveillance is reduced, and the chance of tumor cells eventually transforming into malignant tumors increases. In addition, as one gets older, there is a cumulative effect of cancer-causing factors, with an increasing accumulation of carcinogens in the body. Of course, in terms of internal factors, cancer-causing genes are congenital. There are some people who, although they do not innately carry cancer-causing genes, may develop genetic mutations that lead to the development of malignant tumors. Nowadays, there is a trend of malignant tumors at a younger age. It is hypothesized that, in addition to better diagnostic conditions available, young people are now more susceptible to stimulation by external cancer-causing factors. Carcinogenic factors such as environmental pollution and food additives have increased in modern society. Among malignant tumors, lung, liver and intestinal cancers alone account for 52.01% of deaths. Lung cancer is mainly related to smoking and air pollution; liver cancer has a high incidence in our country and is mainly related to hepatitis B. Bowel cancer, on the other hand, is mainly related to the development of the lung cancer. The occurrence of intestinal cancer is related to the “westernized” tendency of diet, which is high in fat, high in protein, high in calories and low in fiber, all of which are the triggering factors of intestinal cancer. However, the incidence of stomach cancer among Chinese people is decreasing. This is because stomach cancer and rough diet related, if the diet to coarse grains, meat, protein intake is too little, the chances of disease is relatively high, because too coarse grain will make the stomach mechanical friction is very strong. Although cancer has become people’s “number one killer”, but “talk about cancer” is not necessary. The proportion of cancer deaths is increasing year by year, in fact, with the decline in the incidence of other diseases. Moreover, in recent years, the development of medicine has greatly improved the diagnosis and treatment of tumors. For example, under the integrated treatment mode of surgery, radiotherapy, chemotherapy, endocrine therapy, immunotherapy and traditional Chinese medicine, six to seven out of ten people suffering from breast cancer can be cured, and the cure rate of early-stage breast cancer can reach more than 90%. How to make tumors treatable and curable? It has to be realized through three-level prevention. Tertiary prevention is etiological prevention, i.e. abandon smoking, alcoholism, overwork and other lifestyles to reduce the influence of cancer-causing factors on us. Secondary prevention is the so-called “three earlys”: early detection, early diagnosis and early treatment. If you find lumps, ulcers, loss of appetite and weight loss in any part of your body, you should go to the hospital as early as possible for diagnosis and treatment. People should have regular medical checkups and seek immediate medical attention if they find symptoms. Tertiary prevention is the treatment of all malignant tumor patients patients, including those in advanced stages. Nowadays, medicine has been able to achieve the role of striving for the best curative effect, avoiding recurrence and accelerating recovery. Even for advanced patients, it can reduce pain, improve quality of life and prolong survival.