What chemotherapy would you recommend for a patient with Ewing Sarcoma who has relapsed after being initially treated with vincristine/doxorubicin/ifosfamide?  

If the relapse occurred less than 2 years off original chemotherapy, I would use vincristine, irinotecan, and temozolomide. If more than 2 years off, go back to the original regimen. In either case, consider ifosfamide-etoposide if failing to get a CR at the point of maximum response.

It is unclear whether etoposide was inadvertently omitted from the question or was never given to the patient. In either case, the prognosis for recurrent EWS is generally dismal and no standard frontline regimen currently exists. Most would consider cyclophosphamide/topotecan or vincristine/(oral o...