Osteosarcoma refers to a malignant connective tissue tumor in which tumor cells can directly produce tumor bone and bone-like tissue. Its incidence ranks first among primary malignant tumors. The tumor is highly malignant and has extremely poor prognosis. It can metastasize to the lungs within a few months, and the survival rate is only 5% to 20% 3 to 5 years after amputation. About three-quarters of all osteosarcomas occur in the lower end of the femur and the upper end of the tibia, and can also occur in other places such as the humerus, upper end of the femur, fibula, spine, ilium, etc. Most are osteolytic, and a few are osteoblastic. Age of onset: It can occur at any age, but mostly between 10 and 25 years old, and more often in men. The tumor is mostly at the end of the bone, and occasionally occurs in the backbone or epiphysis.