Ewing Sarcoma: Metastatic Tumors
Radiation therapy should be delivered in a setting in which stringent planning techniques are applied by those experienced in the treatment of Ewing sarcoma. Such an approach will result in local control of tumor with acceptable morbidity in most patients. Metastatic sites of disease in bone and soft tissues should receive fractionated radiation therapy doses totaling between 45 Gy and 56 Gy. All patients with pulmonary metastases should undergo whole-lung radiation, even if complete resolution of overt pulmonary metastatic disease has been achieved with chemotherapy.[4,5,12] Radiation doses are modulated based on the amount of lung to be radiated and on pulmonary function. Doses between 12 Gy and 15 Gy are generally used if whole lungs are treated.
More intensive therapies, many of which incorporate high-dose chemotherapy with or without total-body irradiation in conjunction with stem cell support, have not shown improvement in EFS rates for patients with bone and/or bone marrow metastases.[2,3,9,13,14,15] The impact of high-dose chemotherapy with peripheral blood stem cell support for patients with lung metastases is unknown and is being studied in the EURO-EWING-INTERGROUP-EE99 trial. European investigators frequently use high-dose chemotherapy and stem cell support for patients with extrapulmonary metastatic sites; use of high-dose therapy and autologous stem cell reconstitution for patients with metastases at extrapulmonary sites is an investigator choice in the EURO-EWING-INTERGROUP-EE99 (COG-AEWS0331) study. It is not being studied as a randomized prospective question, but the study will acquire data about the outcome of patients treated with this consolidation. Melphalan, at nonmyeloablative doses, has proved to be an active agent in an upfront window study for patients with metastatic disease at diagnosis; however, the cure rate remained extremely low.
Treatment Options Under Clinical Evaluation
The following is an example of an international clinical trial that is currently being conducted. Information about ongoing clinical trials is available from the NCI Web site.
- EURO-EWING-INTERGROUP-EE99 (COG-AEWS0331) (Combination Chemotherapy With or Without Peripheral Stem Cell Transplantation, Radiation Therapy, and/or Surgery in Treating Patients With Ewing Sarcoma): A randomized study for patients with pulmonary metastases only, which is evaluating standard chemotherapy and peripheral blood stem cell transplant versus standard chemotherapy and bilateral lung radiation, is being conducted in Europe and certain cancer centers in the United States. The Children's Oncology Group (COG) member institutions are participating in a limited way in the Euro-Ewing study. Specifically, the study is open through the COG for patients who present with metastases limited to the lung. They will be enrolled in the Euro-Ewing study and will be randomly assigned to receive chemotherapy or high-dose therapy with autologous stem cell reconstitution following induction chemotherapy and local control.