High-dose Chemotherapy Response in Adults with Relapsed/Refractory Small Round Cell Tumours

To demonstrate the treatment responses, survival analysis, and treatment-related mortality characteristics of high-dose chemotherapy (HDC) in patients with relapsed/refractory Ewing sarcoma (ES), osteosarcoma, rhabdomyosarcoma (RMS) and medulloblastoma (MB).

Observational study.

Department of Medical Oncology, University of Health Sciences, Gulhane School of Medicine, from January 2016 and April 2020.

Clinical features and follow-up data of relapsed/refractory ES, osteosarcoma, RMS and MB patients treated with HDC were recorded from the patients' registration database of the hospital. Patients <16 years and those whose medical records were not available were excluded. Progression-free survival (PFS), one-year overall survival (OS) rates and treatment-related mortality (TRM) after the HDC were determined. Ifosfamide, carboplatin and etoposide (HD-ICE) were used as the HDC protocol in all patients.

Thirty-seven adult patients were included. PFS was determined as 2.70 ± 0.97 months, 11.57 ± 3.63 months, 3.47 ± 0.44 months and 2.96 ± 0.91 months, for ES, MB, RMS and osteosarcoma, respectively. One-year OS rate was 44.8 ± 14.8% for ES; 75 ± 15.8% for MB. In ES, PFS was found to be better in males than females (p = 0.025). No patient died during HD-ICE. Mortality was observed most frequently in the RMS in the first 100 days (25%).

HD-ICE treatment may be an option in relapsed/refractory small round cell tumours (SRCT). Significant progression-free survival can be achieved in patients who received at least two lines of treatment, with acceptable treatment-related mortality. Key Words: Small round cell tumours, Ewing sarcoma, Osteosarcoma, Rhabdomyosarcoma, Medulloblastoma, High-dose chemotherapy, Autologous stem cell transplantation.