The treatment of Ewing sarcoma involves a multimodal approach, using surgery and radiation therapy for control of the primary lesion and chemotherapy for eradication of subclinical micrometastases. The preservation of function and the reduction of long-term sequelae should be taken into consideration in determining the treatment.
Because neuroectodermal differentiation does not affect outcome, patients with typical Ewing sarcoma and PPNET are treated with the same protocols as patients with Ewing sarcoma.
Biopsy should be performed at the center at which ultimate surgical treatment will be rendered. The biopsy site should be chosen carefully and placed in line with the potential resection site or radiation portals. The biopsy should be preferably taken from the extraosseous component to prevent pathologic fracture. Frozen section analysis of all biopsy specimens is essential to ensure adequate material has been obtained for light microscopy, electron microscopy, immunohistochemistry, and cyto-genetics. The biopsy site must be included en bloc with the resection or irradiation.
Surgical excision can be used for those tumors in which the removal of the affected bone is not associated with significant functional deficit and in which grossly complete excision can be technically accomplished. Amputation may be more appropriate for tumors involving neurovascular bundle, in young children when reconstruction is not technically feasible, or for tumors of the distal leg or foot.
The following is an approach to the management of the primary lesion in Ewing sarcoma:
1. Preoperative chemotherapy for approximately 9 weeks, if initially not resectable
2. Complete surgical removal after preoperative chemotherapy, if surgery does not cause significant functional impairment
3. Surgical debulking followed by radiation therapy, if complete removal would result in significant functional impairment.
Ewing sarcoma is a radioresponsive tumor. Local control can be achieved in most patients, provided that:
1. A sufficient dose of radiation is administered
2. An adequate volume of normal tissue is in the radiation field.
Current recommendations for radiation of the primary site are doses ranging from 55 to 60 Gy. In the postoperative setting, gross disease requires 55.8 Gy; microscopic disease requires 45 Gy. The appropriate radiation volume is an involved field of the pretreatment tumor plus a 2- to 2.5-cm margin, followed by a boost to the postinduction tumor volume with margin.
Because the incidence of second bone tumors in the irradiated fields ranges from 10-30% at 20 years after therapy, if surgery can be completely performed with adequate function, it is the preferable modality for local control.
The major impact on improved long-term survival in Ewing sarcoma has been systemic chemotherapy. Addition of ifosfamide and etoposide has significantly increased the 5-year event-free (from 54±4% to 69±3%) and overall survivals (from 61±3.6% to 72±3.4%).
Treatment consists of vincristine 2 mg/m2 (maximal dose 2 mg), doxorubicin 75 mg/m2 and cyclophosphamide 1200 mg/m2 followed by mesna alternating with ifosfamide 1800 mg /m2/day for 5 days and etoposide 100 mg/m2/day for 5 days. The courses are administered every 3 weeks for a total of 17 courses with a planned treatment duration of 49 weeks. Doxorubicin is substituted by actinomycin D 1.25 mg/m2/dose when total doxorubicin dose of 375 mg/m2 is reached (after 5 cycles of doxorubicin). Reevaluation and local control occurs at week 12 of chemotherapy.
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