Treatment of metastatic Ewing sarcoma/primitive neuroectodermal tumor of bone: evaluation of increasing the dose intensity of chemotherapy--a report from the Children's Oncology Group.

Background. The outcome for patients with Ewing sarcoma family of tumors (ESFTs) of bone with metastases at diagnosis remains poor despite new approaches to treatment. We evaluated whether a dose-intensity chemotherapy regimen improved survival for patients with ESFTs of bone with metastases at diagnosis. Methods. We entered 60 patients with metastatic ESFTs of bone onto a single arm trial of a new intensive therapy. Treatment consisted of 51-weeks of chemotherapy and local control of the primary with radiation, surgery, or both. The chemotherapeutic protocol included two alternating blocks: one with vincristine (2 mg/m(2)), doxorubicin (90 mg/m2), and cyclophosphamide (2,200 mg/m(2)); and the second with ifosfamide (2,800 mg/m(2)/day x 5 days) and etoposide (100 mg/m(2)/day x 5 days). Results. Of the 60 patients with metastatic ESFTs of bone enrolled onto this single arm trial, 12 had metastasis to lung only, 7 to bone marrow or bone only, 38 to multiple sites, 2 in other sites and 3 not specified. There were three toxic deaths. Six patients (6-year cumulative incidence: 9%) developed second malignant neoplasms and died. The 6-year overall event-free survival (EFS) was 28% (standard error (SE) 6%) and survival (S) was 29% (SE 6%). Conclusion. An intensified treatment regimen using higher doses of cyclophosphainide, ifosfamide, and doxorubicin increased toxicity and risk of second malignancy without improving EFS and S.