Local recurrence after surgical resection is a complex phenomenon. An important predictive factor is the response to chemotherapy. Central site of disease may be a second independent predictive factor (Lin et al. 2007). Patients with more than 10% viable tumour cells at surgery following neo-adjuvant chemotherapy had a less favourable outcome with an Event-free Survival [EFS] of 47% after 10 years. Patients with good histological response (< 10% viable tumour cells) after chemotherapy alone had a prognosis of about 70% after 10 years.

However, further studies are necessary to determine the merit of adjuvant radiation for high-risk patients (poor responders). Taking into consideration that the toxicity and morbidity of combined surgery and radiation is greater than either alone and must be closely monitored.

Inclusion Criteria:

• Age < 18 years old.
• Non-metastatic Ewing Sarcoma patients who will undergo surgery and show poor histologic response to neo-adjuvant chemotherapy.
• Negative surgical margins.
• Patients show good safety profile and acceptable performance status.

Exclusion Criteria:

• Patients who show progressive disease and undergo surgery before the time of local control.
• Patients who undergo Amputation or Rotationplasty will be excluded.
• Post-surgical complications that may hinder the administration of radiotherapy