Tas ML, Nagtegaal M, Kraal KCJM, et al. - In patients with stage 4S neuroblastoma, researchers sought to examine the regression kinetics and risk factors of progression. Study participants included all patients with stage 4S neuroblastoma without MYCN amplification, from two Dutch centers between 1972 and 2012. For this retrospective cohort study, they studied the clinical features, the biochemical activity reflected in urinary catecholamine excretion, and radiological imaging to describe the kinetics of tumor regression, therapy response, and outcome. The 10-year OS was 84% ± 7% in this cohort of 31 individuals. The authors discovered that patients < 4 weeks of age with stage 4S neuroblastoma are at risk of fatal outcomes due to hepatic metastasis progression. In other cases, a rapid biochemical normalization preceding radiological regression is characterized by tumor regression.