Background: Interval compression (IC), a regimen of alternating vincristine/doxorubicin/cyclophosphamide and ifosfamide/etoposide every 2 weeks, improves survival for localized Ewing sarcoma (ES), with uncertain effect on metastatic disease.
Materials and methods: We reviewed the charts of pediatric patients with metastatic ES treated with IC at our center between January 2013 and March 2020. We calculated event-free survival and overall survival (OS) and used log-rank tests for univariate comparisons.
Results: We identified 34 patients 2.7 to 17.1 years of age (median: 11.6 y). Twenty-six patients (76%) had pulmonary metastases, and 14 (41%) had extrapulmonary metastases. All patients received local control therapy: surgery only (n=7, 21%), radiotherapy only (n=18, 53%), or both (n=9, 26%). The estimated 3-year OS and event-free survival were 62%±9% and 39%±9%, respectively. Patients with pulmonary-only and extrapulmonary metastasis had a 3-year OS of 88%±8% and 27%±13%, respectively ( P =0.0074). Age group (above vs. below 12 y), or primary tumor site did not affect survival, but local control therapy did (surgery only, 83%±15%; combined surgery and radiation, 30%±18%; radiation only, 15%±10%; P =0.048).
Conclusion: IC yielded similar outcomes for patients with metastatic ES to other reported regimens. We suggest including this approach to other blocks of therapy.
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