Cancer has a certain relationship with immunity. When normal cells mutate to form cancer cells, the normal immune system of human body will immediately start the immune response to quickly remove the cancer cells to prevent the occurrence of cancer, so as to maintain the stability of human body. When the human immune system has serious defects or deficiencies, it will lead to the occurrence of cancer, and the human body cannot kill the cancer cells that have just started to develop in time, resulting in the continuous development of tumor. It can be said that the whole process of tumor occurrence, development, invasion and metastasis does not involve the immune response and immune regulation of human immunity.