Adolescent-adult nonmetastatic Ewing sarcoma-Experience from a large developing country.

Background: Outcome and toxicity data in adolescent-adult Ewing sarcoma (AA-ES) patients are sparse and merits exploration.
Methods: Histopathologically confirmed, nonmetastatic AA-ES patients, who received standard institutional combination chemotherapy regimen (Ewing's family of tumors-2001 [EFT-2001]) comprising of ifosfamide plus etoposide and vincristine, doxorubicin plus cyclophosphamide, lasting a total of 12 months between 2013 and 2018, were analyzed for treatment-related toxicities, event-free survival (EFS), and overall survival (OS).
Results: There were 235 patients (primary safety cohort [PSC]) with median age of 23 (15-61) years; 159 (67.7%) were males, 155 (65.9%) had skeletal primary and 114 (48.5%) had extremity tumors. One hundred ninety-six (83.4%) were treatment naïve (primary efficacy cohort [PEC]) and of these 119 (60.7%) had surgery. In PEC, at a median follow-up of 36.4 (interquartile range [IQR] 20-55) months, estimated 3-year EFS and OS were 67.3% (95% CI 60.3-75.1%) and 91.1% (95% CI 86.7-95.7%), respectively. Of these, 158 (80.6%) complying with intended treatment, at a median follow-up of 39 (IQR 26-57) months had an estimated 3-year EFS of 68.2% (95% CI 60.3-76.1%). In multivariable analysis, good prognostic factors included longer symptom(s) duration (HR 0.93, 95% CI 0.86-0.994), ≥99% necrosis (HR 0.30, 95% CI 0.11-0.77), and treatment completion (HR 0.32, 95% CI 0.14-0.74). Among PSC, grade 3-4 toxicities were febrile neutropenia (119, 50.6%), anemia (130, 55.3%), peripheral neuropathy (37, 15.7%), with three (1.3%) chemo-toxic deaths.
Conclusions: The outcomes of AA nonmetastatic ES patients treated with EFT-2001 regimen were comparable to those reported by others, with acceptable toxicity. This regimen can be considered a standard of care in AA-ES.
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