Long‐term follow‐up results of pediatric and adolescent patients with localized Ewing sarcoma treated based on stratified modalities

BACKGROUND: Compared with other pediatric tumors, little advances were achieved in studies on the stratified treatment in localized Ewing sarcoma. Most pediatric oncology groups treated Ewing sarcoma according to whether there was an existing metastasis, without involving more prognostic factors. In this study, patients with localized Ewing sarcoma were divided into resectable and unresectable groups at diagnosis and received chemotherapy with different intensity, for the purpose of achieving good efficacy, avoiding overtreatment and reducing unnecessary toxicity. METHODS: A total of 143 patients with a median age of 10 years old diagnosed with localized Ewing sarcoma in this retrospective study were divided into two cohorts (Cohort 1, n = 42; Cohort 2, n = 101) and patients in Cohort 2 received chemotherapy with different intensity (Regimen 1, n = 52; Regimen 2, n = 49). Outcomes were analyzed using the Kaplan-Meier method to estimate event-free survival (EFS) and overall survival (OS), and the curves were compared using the log-rank test. RESULTS: The 5-year EFS and 5-year OS for all the patients were 69.0% and 77.5%. The 5-year EFS for Cohort 1 and Cohort 2 were 76.0% and 66.1% (p = 0.31), and the 5-year OS were 83.0% and 75.1% (p = 0.30), respectively. In Cohort 2, the 5-year EFS rate of patients treated with Regimen 2 was significantly higher than that of patients treated with Regimen 1 (74.5% vs. 58.3%, p = 0.03). CONCLUSIONS: According to whether a grossly complete resection was received at the time of diagnosis, localized Ewing sarcoma patients in this study were stratified into two groups and received different intensities of chemotherapy, which achieved good efficacy and avoided overtreatment and reduced unnecessary toxicity.