Patients
We retrospectively analyzed data pertaining to patients with refractory (defined as inadequate response to treatment that included at least 4 cycles of ≥2 chemotherapeutic agents, including an alkylator and a platinum-containing compound) or relapsed neuroblastoma who underwent IREC therapy at the Nagoya University Hospital between October 2013 and March 2020. Written informed consent for treatment with the IREC regimen was obtained from the patients or their parents prior to the start of chemotherapy. This study was approved by the ethics committee of the Nagoya University Graduate School of Medicine and was conducted in accordance with the principles of the Declaration of Helsinki.