Local control for Ewing tumor of bone
Treatment approaches for ESFT 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.
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 ESFT 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. 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.
High-Dose Therapy with Stem Cell Rescue for Ewing Tumor of Bone
For patients with a high risk of relapse with conventional treatments, certain investigators have utilized high-dose chemotherapy with hematopoietic stem cell transplant (HSCT) as consolidation treatment, in an effort to improve outcome.[20,21,22,23,24,25,26,27,28,29] In a prospective study, patients with bone and/or bone marrow metastases at diagnosis were treated with aggressive chemotherapy, surgery, and/or radiation and HSCT if a good initial response was achieved. The study showed no benefit for HSCT compared with historical controls. Multiple small studies that report benefit for HSCT have been published but are difficult to interpret because only patients who have a good initial response to standard chemotherapy are considered for HSCT. The role of high-dose therapy followed by stem cell rescue is being investigated in a Euro-Ewing clinical trial (EURO-EWING-INTERGROUP-EE99) for patients that present with pulmonary metastases.