High‐dose chemotherapy followed by autologous haematopoietic cell transplantation for children, adolescents, and young adults with primary metastatic Ewing sarcoma

Background Ewing sarcomas are solid tumours of the bone and soft tissue, that usually affect children, adolescents, and young adults. The incidence is about three cases per million a year, with a peak incidence at 12 years of age. Metastatic disease is detected in about 20 % to 30% of people, and is typically found in the lungs, bone, bone marrow, or a combination of these. Presence of metastatic disease at diagnosis (primary metastatic disease) is the most important adverse prognostic factor, and is associated with a five-year survival lower than 30%. High-dose chemotherapy (HDC) followed by autologous haematopoietic cell transplantation (AHCT) is used in various solid tumours with unfavourable prognoses in children, adolescents, and young adults. It has also been used as rescue after multifocal radiation of metastases. The hypothesis is that HDC regimens may overcome the resistance to standard multidrug chemotherapy and improve survival rates. Objectives To assess the effects of high-dose chemotherapy with autologous haematopoietic cell transplantation compared with conventional chemotherapy in improving event-free survival, overall survival, quality-adjusted survival, and progression-free survival in children, adolescents, and young adults with primary metastatic Ewing sarcoma, and to determine the toxicity of the treatment. Search methods We searched CENTRAL, MEDLINE, Embase, conference proceedings from major international cancer-related conferences, and ongoing trial registers until January 2020. We also searched reference lists of included articles and review articles. Selection criteria We included randomised controlled trials (RCTs) or (historical) controlled clinical trials (CCTs) comparing the effectiveness of HDC and AHCT with conventional chemotherapy for children, adolescents, and young adults (younger than 30 years at the date of diagnostic biopsy) with primary metastatic Ewing sarcoma. Data collection and analysis We used standard methodological procedures expected by Cochrane. Main results We identified one RCT, which investigated the effects of HDC with AHCT versus conventional chemotherapy with whole lung irradiation (WLI) in people with Ewing sarcoma metastasised to the lungs only at diagnosis. Only a selection of the participants were eligible for our review (N = 267: HDC with AHCT group N = 134; control group N = 133). There may be no difference in event-free survival between the two treatment groups (hazard ratio (HR) 0.83, 95% confidence interval (CI) 0.59 to 1.17; low-certainty evidence). We downgraded one level each because of study limitations and imprecision. Overall survival and toxicity were not reported separately for the participants eligible for this review, while quality-adjusted survival and progression-free survival were not reported at all. We did not identify any studies that addressed children, adolescents, and young adults with Ewing sarcoma with metastases to other locations. Authors' conclusions In people with Ewing sarcoma with primary metastases to locations other than the lungs, there is currently no evidence from RCTs or CCTs to determine the efficacy of HDC with AHCT compared to conventional chemotherapy. Based on low-certainty evidence from one study (267 participants), there may be no difference in event-free survival between children, adolescents, and young adults with primary pulmonary metastatic Ewing sarcoma who receive HDC with AHCT and those who receive conventional chemotherapy with WLI. Further high-quality research is needed. Results are anticipated for the EuroEwing 2008R3 study, in which the effects of HDC with treosulfan and melphalan followed by AHCT on survival, in people with Ewing sarcoma with metastatic disease to bone, other sites, or both were explored. Achieving high-quality studies in a selection of people with rare sarcoma requires long-term, multi-centre, international participant inclusion.