Characterization of Clinical Outcomes for Patients with Relapsed High-Risk Neuroblastoma After Autologous Stem Cell Transplant and External Beam Radiotherapy

Background: Limited data inform the outcomes of patients with high-risk neuroblastoma (HR-NBL) who relapse after high-dose chemotherapy, autologous stem cell transplantation (ASCT), and external beam radiotherapy (EBRT). Methods: This is a multi-institutional retrospective study of 84 patients with HR-NBL diagnosed between 1997–2021 with a first recurrence after definitive upfront treatment, including ≥1 ASCT and EBRT. Site(s) of first relapse were defined with relation to a patient’s primary tumor location. Progression-free survival (PFS) and overall survival (OS) outcomes were analyzed using Kaplan–Meier curves and log-rank tests. Cox proportional hazard models were used for univariate and multivariable analyses. Results: Twenty-four patients had local recurrences with or without distant relapses (LR) and 60 had distant relapses only. The LR cohort had higher rates of MYCN amplification (70% vs. 36%, p = 0.016). At relapse, the LR cohort had lower rates of additional radiotherapy (32% vs. 61%, p = 0.029) and higher rates of additional surgery (29% vs. 5%, p = 0.005), with similar rates of chemotherapy for both cohorts. With a median follow-up after first relapse of 1.53 years (range: 0.03–15.82), there were no significant differences in interval PFS and OS between the cohorts. After controlling for age at diagnosis and pattern of recurrence, time to interval relapse ≥ 2 years was a significant predictor of improved OS (HR: 0.50, 95% CI: 0.29–0.85, p = 0.011). Conclusions: Patients with relapsed HR-NBL have poor outcomes with median OS < 2 years. Time to relapse was a significant predictor of OS.