This prospective observational study evaluates serial circulating tumor DNA (ctDNA) and molecular residual disease (MRD) monitoring in patients with neuroblastoma. The study aims to characterize baseline genomic alterations, assess ctDNA detectability and dynamic changes during treatment and follow-up, compare tumor-informed personalized MRD assays with fixed-panel assays, and determine the clinical utility of ctDNA/MRD for treatment response assessment, molecular remission evaluation, relapse surveillance, and early detection of disease progression.