There are benign and malignant tumors. Benign tumors are generally slow-growing, have a peripheral membrane and clear boundaries, so they are easy to be surgically removed cleanly and generally do not recur. On the other hand, malignant tumors grow faster, invade and destroy the surrounding normal tissues, and can even be transferred to other parts of the body through lymphatic vessels, blood vessels or body cavities to “settle and proliferate” in other parts of the body, and ultimately deplete the human body. There are many factors affecting the recurrence of malignant tumors after surgical resection: first, the nature of the tumor itself. First, the nature of the tumor itself. From the pathological point of view, each malignant tumor has its own different characteristics. Some are malignant but relatively mild, which we call low malignancy, and rarely recur or metastasize after surgical resection. On the other hand, some are fast-growing, highly invasive and easy to metastasize, and may have extensive lymph node or bloodstream metastasis even though the tumor itself is small in size, which we call highly malignant and very prone to recurrence after surgery. Second, the duration of the disease, that is, the time between the onset of the disease and the treatment. Let’s take gastrointestinal tumors as an example. If the pathological diagnosis is intramucosal cancer, it is in the early stage of gastric cancer, timely surgical resection, low recurrence rate and good prognosis. If the pathological diagnosis is progressive cancer or has been accompanied by lymph node metastasis, it suggests that it is already advanced gastric cancer, with high recurrence rate and poor prognosis after surgery. Third, the scope of surgery. Malignant tumor has unclear boundary with surrounding tissues, which is often described as tree root-like infiltrative growth in medicine, and the scope of local resection is not enough, which is bound to recur. Therefore, the choice of what kind of surgery is an important issue for doctors to consider before surgery. A reasonable surgical method should not only consider the complete removal of the tumor, but also take into account whether the patient’s physical condition can withstand it and consider the patient’s quality of life and many other issues. Fourth, it is the patient’s own physical and nutritional status. The patient’s preoperative physical condition and postoperative recovery can affect the body’s ability to fight against cancer cells, and in a weaker body, the growth of residual cancer cells in the body may easily gain the upper hand and “rekindle”. On the contrary, if the body’s immunity is strong, the residual tumor cells can be eliminated through autoimmune response. Therefore, strengthening nutrition and improving immunity has always been the basic therapy for fighting cancer. All in all, the fundamental reason for the recurrence of malignant tumors is that even if the main tumor is removed, there may still be a small number of residual tumor cells in the body, which grow and develop continuously, eventually leading to clinical recurrence. Tumor patients should undergo regular radiotherapy or chemotherapy under the guidance of clinicians after surgical resection in order to nip the possible residual tumor cells in the bud and prevent tumor recurrence to the maximum extent.