Outcomes with nondose-dense chemotherapy for Ewing sarcoma: A practical approach for the developing world

Background The current multidisciplinary approach in the treatment of Ewing sarcoma has improved cure rates, with contemporary dose-dense chemotherapy attaining 5-year event-free survival (EFS) of 73% in localized cases. Dose-intense and dose-dense chemotherapy is difficult in the majority of resource-limited settings with limited access to optimal supportive care. We report on patients with Ewing sarcoma treated on EFT-2001, a nondose-dense chemotherapy protocol. Procedure A retrospective analysis was conducted of patients (<15 years) with Ewing sarcoma treated with curative intent during January 2013-June 2017 with an institutional ethics committee-approved nondose-dense protocol (EFT-2001). Local therapy was planned after 9-12 weeks of chemotherapy with metastatic sites addressed with radiotherapy. The study assessed outcomes and prognostic factors. Results We analysed 200 patients with M:F ratio of 1.27:1 and metastases in 41 patients (20.5%). At a median follow up of 41.5 months (range 4.5-81.8 months), respective 3-year EFS and overall survival (OS) of the whole cohort is 65.3% (95% confidence interval [CI]: 58.1-71.7%) and 79.3% (95% CI: 72.8-84.5%); for localized and metastatic cohort, 70.9% (95% CI: 62.9-77.5%) and 82.8% (95% CI: 75.7-89.0%); and for metastatic cohort, 42.8% (95% CI: 28.0-58.6%) and 65.3% (95% CI: 47.7-78.3%). Presence of residual disease (morphologic/metabolic) on positron emission tomography-computed tomography scan done 3 months post definitive radiotherapy (hazard ratio [HR] 7.92 [95% CI: 3.46-18.14]) and delay in any form of local control >4 months (HR 3.42 [95% CI: 1.32-8.89]) affected outcomes. Nonrelapse mortality during treatment was 6.5%, mainly due to cardiomyopathy (3.0%) and bacterial sepsis (1.5%). Cardiotoxicity was seen in 11.5% of patients. Conclusions Nondose-dense chemotherapy provides good outcomes with manageable toxicities in a multidisciplinary treatment approach, while reducing cumulative drug exposures in the developing world where dose-intense or dose-dense chemotherapy could potentially increase toxicity, and hence seems a feasible approach in resource-limited settings. Presence of any residual disease post definitive radiotherapy or delay in local control portends poor outcome.