A low-grade malignant tumor is a tumor that is formed when the tumor cells are more differentiated and similar to normal cells. The growth rate of low-grade malignant tumors is slow, and some tumors can remain unchanged for several years, such as low-grade malignant non-Hodgkin’s lymphoma, which has swollen lymph nodes in the neck that can remain unchanged for several years. In addition, the aggressiveness and metastasis of low-grade malignant tumors are relatively low, and therefore its prognosis is better. Currently, the treatment for low-grade malignant tumors is based on radical surgical resection, and postoperative adjuvant chemotherapy and adjuvant radiotherapy against tumors are generally not required. There are also patients who only need observation without other treatment, such as low-grade malignant non-Hodgkin’s lymphoma, which can only be observed clinically without anti-tumor treatment. For patients with stage III or IV, a combination of radiotherapy and chemotherapy can be considered.