Serial ctDNA and Molecular Residual Disease Monitoring in Neuroblastoma

Inclusion Criteria: * Patients with histologically or clinically confirmed neuroblastoma according to institutional or protocol-defined diagnostic criteria. Newly diagnosed, relapsed, refractory, or progressive neuroblastoma eligible for serial biospecimen collection during routine clinical care. Availability of peripheral blood samples for ctDNA/MRD analysis at baseline and/or longitudinal follow-up time points. Availability of clinical data required for molecular-clinical correlation analyses, including response and outcome assessment. Availability of tumor tissue and matched control samples for tumor-informed assay development, if applicable and feasible. Written informed consent from a parent or legal guardian, and assent from the participant when applicable. Exclusion Criteria: * Inability to provide protocol-required blood samples for ctDNA/MRD testing. Insufficient clinical information for protocol-defined response or outcome analyses. Poor-quality or insufficient biospecimens that preclude molecular analysis, when molecular testing is a required component of the study dataset. Any condition that, in the opinion of the investigator, would make study participation inappropriate.