Chemotherapy for osteosarcoma – The significance of preoperative chemotherapy is to determine the sensitivity of the tumor to chemotherapy and to adjust the postoperative chemotherapy regimen for those who are not sensitive in order to improve the tumor-free survival rate. From the perspective of tumor growth kinetics, tiny metastases are more sensitive to chemotherapy than large primary foci and smaller metastases. In order to avoid the delay of waiting for surgery and recovery period after surgery, and to eliminate metastases, control primary foci and cooperate with surgery more effectively, chemotherapy for osteosarcoma has been changed from simple postoperative chemotherapy to comprehensive chemotherapy before and after surgery. Many scholars point out that tumor necrosis after chemotherapy is an important indicator to judge the prognosis. In patients with neoadjuvant chemotherapy for osteosarcoma of the limb, chemotherapy-induced necrosis, in addition to being associated with the long-term outcome of treatment, is also an independent factor affecting local recurrence. Bacci et al. noted that in neoadjuvant chemotherapy treatment of osteosarcoma, the degree of necrosis in resected tumor specimens predicted disease-free survival (DFS), and the higher the degree of necrosis in the primary tumor, the higher the disease-free survival. Therefore, in the past, the main strategy to improve the prognosis of osteosarcoma has been the use of remedial postoperative chemotherapy for patients who have had a poor response to preoperative chemotherapy. However, these attempts to modify disease-free survival in poor responders have had limited success. A wise strategy is to use more potent and powerful preoperative chemotherapy for oncologic chemotherapeutic necrosis.