What should patients who have already had surgery do to prevent their re-occurrence? 1. Don’t smoke. Cigarette smoke contains many carcinogenic substances, such as benzo(a)pyrene, dimethylnitrosamine, radioactive element ZIOPO and phenolic compounds, and other serious harmful substances such as nicotine, carbon monoxide and tar, etc. About 70%-80% of lung cancer patients in China are caused by long-term smoking. Qi Kelei, Department of Thoracic Surgery, Hebei Chest Hospital 2.Promote scientific dietary structure. More than 65% of gastrointestinal cancers in China are mainly related to drinking water pollution, improper dietary structure or pollution, the structure of fat, protein and carbohydrates in the diet should be in healthy proportion, mainly plant foods, with appropriate vegetables, avoid high fat, high protein and high calorie diet, which can reduce the occurrence of rectal cancer, colon cancer, prostate cancer, pancreatic cancer, breast cancer, endometrial cancer, ovarian cancer, etc. This can reduce the occurrence of rectal, colon, prostate, pancreatic, breast, endometrial and ovarian cancers. 3.Do not drink alcohol or drink less alcohol. It has been proved that women who drink 20-30 grams of alcohol per day are two times more likely to develop breast cancer than those who do not drink alcohol. 4.Prevent food contamination. Mainly prevent the infection or spread of cancer-causing microorganisms, and strictly control and monitor food additives.