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The natural courses of osteosarcoma and Ewing sarcoma have been changed due to the development of chemotherapy. In osteosarcoma, chemotherapy prevents the occurrence of distant metastasis and also provides the possibility of limb sparing surgeries. However, there is a controversy in selecting drugs in the treatment of this tumor. Ewing sarcoma, today is accepted as a systemic disease and chemotherapy is the primary treatment in this tumor. On the other hand, Iocal control of the primary tumor is also an important factor in its course.