The occurrence and development of tumors are mostly related to environmental factors, and dietary health, living habits and air pollution are all influencing the occurrence of the disease. Experts believe that tumors can be prevented and treated. Firstly, primary prevention, advocating healthy lifestyle, reducing cancer-causing factors, insisting on physical exercise and maintaining optimistic mood are very important to prevent tumors. Secondly, secondary prevention is to conduct regular body check-ups to achieve early detection, early diagnosis and early treatment. The last is tertiary prevention, which is to provide active and correct medical treatment for diagnosed cancer patients to strive for the best curative effect. In fact, cancer cells have a “dormant period” of 3~5 years. Once the external environment or the patient’s own immunity decreases, recurrence and metastasis may occur. Cancer patients have cancer because their body environment has “cancerous constitution”, surgery, radiotherapy and chemotherapy have killed cancer cells, but without physical regulation and immune regulation, it is difficult to recover from cancer. Surgery, radiotherapy and chemotherapy kill cancer cells, but without physical and immune regulation, it is difficult to solve the problem of cell differentiation and regulation mechanism disorder in patients’ body, and cannot change their “cancerous constitution”. Therefore, the living environment of cancer cells is not changed, and surgery and radiotherapy cannot stop the production of new cancer cells, so the recurrence and metastasis of tumors are inevitable. 2.Incomplete surgery Surgery can remove cancer cells that have formed lumps, radiotherapy and chemotherapy can kill all or some adult cancer cells, but they are not good for juvenile cancer cells. Once the juvenile cancer cells wake up from dormancy, they will rapidly fission and mutate to form new adult cancer cells, which is the root cause of cancer metastasis and recurrence. 3.No regular follow-up Cancer can kill people because of its aggressiveness, recurrence and metastasis. The key to prevent recurrence is to obtain eradication at the initial treatment and regular follow-up after treatment. Recurrence of cancer often occurs within five years after treatment, especially within two to three years, and it is very important to follow up during this period of time to “kill” new cancer cells as soon as they are found. Regular follow-ups are lifelong, and the closer to the end of treatment, the shorter the interval between follow-ups should be. It is understood that, different from the DC-CIK immunotherapy in the past, the current multi-cell therapy program applied to tumor mainly uses DC cells to mediate active immunotherapy, and NK, γδT, CIK, CD3Ak cells as representatives to mediate passive immunotherapy, combining active and passive immunity, combining multiple immune cells, on the basis of the respective advantages of each immune cell to kill tumor. It can enhance the body’s own immune ability, mobilize the body to participate in immune response, and jointly form a multi-angle and multi-directional three-dimensional killing advantage against tumor cells, so as to achieve more significant anti-cancer effect.