Ewing Sarcoma: A 15-Year Experience of a Single Center With the MSKCC P6 Treatment Protocol.

Introduction: Ewing sarcoma (ES) is the second most common bone tumor in children. Current chemotherapeutic regimens include high-dose anthracyclines and alkylating agents with significant variation in treatment length. The Memorial Sloan Kettering Cancer Center P6 regimen (MSKCC P6) treatment protocol is a highly aggressive regimen given over 21 weeks only. We present the outcome of ES patients treated in our center with this protocol over the last 15 years. Procedure: We retrospectively analyzed data on the presentation, patient characteristics, treatment, and outcome of all ES patients treated according to the MSKCC P6 regimen from 1999 to 2014. Results: Of 48 patients, 37 (77%) presented with a nonmetastatic disease and 26 (54%) with tumor located in the extremities. The 5-year overall survival (OS) of the entire cohort was 55.9%+/- 8%. Nonmetastatic disease conferred a better prognosis with a 5-year OS of 68.4%+/- 8.5%. Patients with a nonmetastatic extremity tumor had the most favorable outcome with 5-year OS of 72.2%+/- 9.8%. Conclusion: The outcome of ES patients after a short aggressive course of chemotherapy (the MSKCC P6 protocol), is comparable to that following other first-line treatment regimens in use, with potentially fewer long-term adverse events.