Since the 1970s, the incidence and mortality rates of cancer in China have been on the rise. Research has shown that 80 per cent of the causes of cancer are related to lifestyle behaviors. Therefore, some experts have put forward the concept of “lifestyle cancer”. Lifestyle is a behavioral tendency or behavioral pattern formed by individuals and groups in the process of long-term socialization. Health-related lifestyle includes diet, study, labor, rest, exercise, personal hygiene, family hygiene, interpersonal communication, protection of the environment and other aspects. Lifestyle is actually a habit of life. A report released by Cancer Research UK shows that more than 40% of the cancer patients diagnosed in the UK each year are caused by poor lifestyles such as smoking, drinking, lack of vegetables and fruits, and physical inactivity. Therefore, clothing, food, housing and transportation may all cause “lifestyle cancer”, of which smoking, alcoholism, diet and exercise are most closely related to cancer. The relationship between smoking and alcoholism and cancer is omitted here because they are well-known causes of cancer. Diet and Cancer In recent years, a large number of epidemiological and etiological studies on esophageal cancer have been conducted both at home and abroad, indicating that the high incidence of esophageal cancer is related to low socio-economic status, poor dietary habits, history of diseases and family heredity, among which the dietary factor occupies an important position. Pickled food, irregular diet, moldy food, hot food, high salt diet, fast eating speed and pickles are risk factors for esophageal cancer. Pickled food and moldy food contain nitroso compounds, which have a strong carcinogenic effect on most animals. Eating hot food for a long time makes the esophageal mucosa damaged, and scalded food above 70 degrees will have a serious effect on the proliferation cycle of the esophageal mucosal epithelial cells, and creates favorable conditions for the cells to produce cancer under the action of harmful metabolic products. Poor dietary practices such as fast eating speed and irregular diets have emerged with the increase in social pressure and the acceleration of the pace of life. When food lacks sufficient chewing, rough substances in food damage the esophageal mucosa for a long time, especially in the physiological narrowing area. Long-term dietary irregularities will lead to esophageal movement and coordination disorders and cause damage to the esophagus. Gastric cancer is mainly a malignant tumor due to environmental factors (including lifestyle). Epidemiological investigation data of stomach cancer at home and abroad show that poor dietary habits (irregular meals, overeating, fast eating, liking hot food, etc.) are risk factors for stomach cancer. If poor dietary habits, it is easy to form the overburden of stomach, causing mechanical gastric mucous membrane damage and gastric juice secretion disorder, which will lead to the occurrence of chronic gastric disease in the long run. Chronic gastric disease, especially atrophic gastritis, destroys the protection and barrier function of gastric mucosa and increases the risk of carcinogens. In addition, frequent consumption of preserved food raises the risk of gastric cancer. Animal experiments and epidemiological studies have found that the intake of preserved food is positively correlated with gastric cancer. A large body of epidemiologic data suggests that high-fat diets significantly increase the incidence of colorectal cancer. Studies have shown that a diet of saturated fatty acids increases the concentration of bile acids in the colon and alters the composition of the colonic flora, which by bacterial action can produce certain carcinogens. Dietary fiber, on the other hand, has the effect of absorbing water, increasing the volume of feces, diluting the concentration of intestinal residues, and shortening the time that feces passes through the large intestine, thereby reducing the time that carcinogens come into contact with the mucosa of the colon. Therefore, high-fat diet and insufficient dietary fiber are important factors triggering colorectal cancer. In addition, diets high in refined sugar, especially sucrose, may increase the risk of colon and rectal cancer. Many studies have shown that factors such as high fat, low vegetables, large body mass index (BMI) and high body fat content can increase the incidence of breast cancer in women. Foreign scholars have reported that the risk of breast cancer in people with high-fat, low-fiber diets is twice as high as that in people with low-fat, high-fiber diets. Many studies have found that there is a correlation between obesity and breast cancer, and the earlier the age of obesity, the greater the risk of breast cancer. Frequent consumption of fried and barbecued foods and smoked and preserved foods (>50 grams 3 times/week) are stronger risk factors for breast cancer.