The effectiveness of high-dose chemotherapy with autologous hematopoietic stem cell transplantation in the treatment of children and young adults with Ewing sarcoma

Abstract

Background. Ewing sarcoma (EWS) is a second most common pediatric bone tumor. About one quarter of all patients belong to a high-risk group characterized by a poor prognosis. In spite of high-dose chemotherapy (HDCT) with autologous hemopoietic stem cell transplantation (auto-HSCT) being traditionally viewed as a possible option for high-risk patients, there is stills no consensus on indications for this method in EWS patients. Study objective: to evaluate the HDCT effectiveness and most important prognostic factors in a prospective cohort of high-risk EWS patients. Materials and methods. A total of 73 EWS patients receiving treatment in R. M. Gorbacheva Memorial Institute were included in the study. All patients were characterized by one or several high-risk features: local (primary tumor volume >200 ml, axial localization, poor response to chemotherapy; n = 55; 76 %), primary disseminated disease (n = 58; 80 %), first chemoresponsive relapse (n = 7; 9 %). All patients received a myeloablative consolidation regimen consisting of busulfan 16 mg / kg and melphalan 140 mg / m2. In patients with primary disseminated disease an additional evaluation according to risk scale by R. Ladenstein et al. was performed. Based on risk points all patients were stratified as standard (n = 20), high (n = 26), and ultrahigh risk (n = 12). Results. The 5-year overall and event-free survival for a whole studied cohort were 40 and 37 %, accordingly. In patients with high-risk localized disease the 5-year overall and event-free survival were 48 and 45 %, accordingly. The HDCT regimen was characterized by acceptable toxicity. The main non-hematologic toxicities were infectious complications (n = 61) and gastrointestinal tract mucositis (n = 31). One patient of 76 died due to treatment-related complications. The multivariate analysis revealed the following risk factors: therapy response (hazard ratio (HR) 2.2; p <0.01), bone marrow involvement (HR 5.0; p = 0.01), primary tumor volume (HR 1.9; p = 0.01), and number of bone metastases (HR 2.2; p = 0.05). The risk group determined by R. Ladenstein score was also a good predictor for outcome with only 8 % of ultrahigh risk patients surviving 5 years past auto-HSCT. Conclusion. HDCT with auto-HSCT may potentially improve treatment results in some high-risk patient subgroups. While risk scale may help to determine patients most likely to benefit from this approach, the outcome in ultrahigh risk patients are still dismal.