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/m(2)), 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 cyclophosphamide, ifosfamide, and doxorubicin increased toxicity and risk of second malignancy without improving EFS and S.