The duration of primary chemotherapy ranges from 6 months to approximately 1 year. A randomized clinical trial (COG-AEWS0031 [NCT00006734]) from the Children's Oncology Group showed that for patients presenting without metastases, the administration of cycles of cyclophosphamide, doxorubicin, and vincristine alternating with cycles of ifosfamide and etoposide at 2-week intervals achieved superior EFS (5-year EFS, 73%) than alternating cycles at 3-week intervals (5-year EFS, 65%).
Local control for Ewing sarcoma
Treatment approaches for Ewing sarcoma titrate therapeutic aggressiveness with the goal of maximizing local control while minimizing morbidity.
While surgery is effective and appropriate for patients who can undergo complete resection with acceptable morbidity, children who have unresectable tumors or who would suffer loss of function are treated with radiation therapy alone. Those who undergo gross resections with microscopic residual disease may benefit from adjuvant radiation therapy. Randomized trials that directly compare both modalities do not exist, and their relative roles remain controversial. Although retrospective institutional series suggest superior local control and survival with surgery rather than radiation therapy, most of these studies are compromised by selection bias. Data for patients with pelvic primary Ewing sarcoma from a North American intergroup trial showed no difference in local control or survival based on local-control modality—surgery alone, radiation therapy alone, or radiation plus surgery.
For patients who undergo gross total resection with microscopic residual disease, the value of adjuvant radiation therapy is controversial. Investigations addressing this issue are retrospective and nonrandomized, limiting their value. Investigators from St. Jude Children's Research Hospital reported 39 patients with localized Ewing sarcoma who received both surgery and radiation. Local failure for patients with positive and negative margins was 17% and 5%, respectively, and overall survival (OS) was 71% and 94%, respectively. However, in a large retrospective Italian study, 45 Gy adjuvant radiation therapy for patients with inadequate margins did not appear to improve either local control or disease-free survival. It is not known whether higher doses of radiation therapy could improve outcome. These investigators concluded that patients who are anticipated to have suboptimal surgery should be considered for definitive radiation therapy.
Thus, surgery is chosen as definitive local therapy for suitable patients, but radiation therapy is appropriate for patients with unresectable disease or those who would experience functional compromise by definitive surgery. The possibility of impaired function needs to be measured against the possibility of second tumors in the radiation field (see below). Adjuvant radiation therapy should be considered for patients with residual microscopic disease, inadequate margins, or who have viable tumor in the resected specimen and close margins.
When preoperative assessment has suggested a high probability that surgical margins will be close or positive, preoperative radiation therapy has achieved tumor shrinkage and allowed surgical resection with clear margins.