[Local therapy of Ewing sarcoma: radiotherapy aspects].

In CESS 86, radiotherapy and surgery as local treatment modalities yielded the same survival rates. Irradiated patients developed more local recurrences as compared to surgically treated patients (14% versus 4%), but less systemic metastases (16% versus 28%). The local recurrence rate after definitive radiotherapy dropped from 50% in CESS 81 to 14% in CESS 86. This was probably caused by an earlier start of radiotherapy (in week 10 in CESS 86 as compared to week 19 in CESS 81) and the high quality of radiation therapy in CESS 86 due to central treatment planning (only 2% protocol violations). Patients with local recurrences showed no differences in the distribution of major prognostic parameters (tumor volume, response to chemotherapy) as compared to patients with local control of disease. As a consequence of these results the concept of early irradiation with subsequent "consolidant" surgery for high-risk patients has been established.