All organs and tissues of the human body are composed of billions of cells, which under normal conditions are born, grow, age and die in a certain way and at a certain rate, metabolizing regularly and maintaining the normal functions of the body. When the body is subjected to certain factors for a long time, there is excessive proliferation or abnormal differentiation and a new organism is formed. The unrestrained and uncontrolled growth of this new organism is clinically manifested as a local mass, which is a tumor. Tumors can occur in any part of human body except hair, teeth and finger (toe) nails, and can occur at any age. Tumors are divided into benign tumors and malignant tumors. In benign tumors, tumor cells are close to normal cells in morphology and function, with slow growth and “expansive growth”, i.e. tumors only have a pushing and squeezing effect on surrounding normal tissues, often with envelope and clear demarcation, and have a certain “self-limiting” growth. The tumor cells will not be shed from the primary site and metastasize to other sites to form new metastases. Therefore, most benign tumors can be completely removed without recurrence, which is what we call “cure” and less harmful to human body. The structure and function of malignant tumor cells are different from normal cells, and the growth mode is “infiltrative growth”, that is, there is no obvious boundary between the tumor and the surrounding normal tissues, and the demarcation is unclear. The tumor cells are shed from the tumor body and run to other places through lymphatic vessels, blood vessels or other cavities to form new metastases. In addition to causing symptoms of compression and obstruction, malignant tumors may also be combined with bleeding, necrosis and fever. Malignant tumors are difficult to be completely removed, easy to recur after surgery, and often metastasize to local lymph nodes or spread to the whole body, making it difficult to be completely cured, which often leads to patients’ death eventually. Cancer is a malignant tumor originated from epithelial tissues, which is called “cancer” in English, directly translated as “crab”, figuratively describing its “open teeth and claws” growth and “rampant” growth. It is called “cancer” in English, which is directly translated as “crab”, describing its characteristics of growing with “teeth and claws” and invading with “rampant”. When people hear the term “cancer”, most people think it is a single disease. In fact, this term includes more than 200 diseases. To be precise, malignancy includes cancer.