Treatment of pediatric patients with localized Ewing sarcoma

Introduction. Localized Ewing sarcoma (ES) is a rare aggressive malignant neoplasm coming from small blue round cells, affecting bones and soft tissues, diagnosed most often in adolescents and young adults. ES accounts for 2% of all malignant neoplasms in children and 27% of all primary malignant bone tumors in patients aged 15–29 years. From 2012 to 2024, the musculoskeletal sarcoma research group of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology registered patients in the unified database and coordinated all stages of diagnosis and treatment of children and adolescents with ES in cooperation with regional clinics. Aim: to analyse the effectiveness of treatment in patients with localized form of ES treated according to the EWING 2008 or Euro Ewing 2012 protocols in the Russian Federation. Materials and methods. The prospective study included 193 patients with localized ES, registered by the musculoskeletal sarcoma research group at the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology between 2012 and 2024. The patients received chemotherapy based on the EWING 2008 protocol and arm B of the Euro Ewing 2012 protocol. Initial patient characteristics, overall (OS) and event-free (EFS) survival were evaluated depending on tumor localization, treatment regimen, extent of surgical resection, pathologic response to treatment. Results. Treatment according to arm B of the Euro Ewing 2012 protocol proved to be more effective than the previously used chemotherapy according to the EWING 2008 protocol (5-year EFS in the Euro Ewing 2012 and EWING 2008 groups: 74.2 ± 5.1% and 68.0 ± 5.2%, respectively (p = 0.5053), 5-year OS in the Euro Ewing 2012 and EWING 2008 groups: 90.1 ± 3.9% and 83.8 ± 4.1%, respectively (p = 0.3257)). Three-year EFS of patients with localized ES who received high-dose chemotherapy exceeded the results of the Euro Ewing study group: 83.6 ± 8.7% versus 69.0% (95% confidence interval 60.2–76.6), respectively. Conclusion. The obtained statistical results of OS and EFS are consistent with global data, but we identified several features characteristic of the Russian population.