Ewing's sarcoma mainly develops in the bones of the pelvis, ribs, femora, fibula, and tibia. It has a strong invasive power and it is therefore not uncommon to see other cancerous foci appear in the body, especially in the lungs, skeleton and bone marrow. It often poses difficult therapeutic problems. Treatment is most often based on a combination of chemotherapy, radiotherapy and surgery. The overall cure rate is around 65%, but it is very uneven from one form to another. While the 5-year survival of localized forms of Ewing's sarcoma can reach 80%, it is less than 20% in metastatic forms.