Primary prevention of tumors refers to the elimination or reduction of potentially cancer-causing factors to prevent the development of cancer. In clinical practice, cancer is caused by many different factors interacting with each other, such as environment, nutrition and diet as well as genetics, viral infection and lifestyle choices. Cancer can be prevented. Early diagnosis and early treatment can reduce patients’ pain and prolong their life span. The prevention of cancer is divided into three levels of prevention: primary prevention refers to the elimination or reduction of possible cancer-causing factors to prevent the occurrence of cancer; secondary prevention refers to how to detect cancer in its early stage and treat it timely once it occurs; tertiary prevention, i.e. the rehabilitation after diagnosis and treatment, improves the quality of patients’ survival, alleviates pain and prolongs their lives. Generally speaking, cancer can be cured if reasonable prevention is carried out.