Is the prognosis of stage 4s neuroblastoma in patients 12 months of age and older really excellent

Abstract Purpose In the International Neuroblastoma Risk Group (INRG) classification system, stage 4s was changed into stage MS in children less than 18 months of age. Stage MS is defined as a metastatic disease with skin, liver and bone marrow, similar to INSS stage 4s. To evaluate the outcome of stage 4s cases in patients 12 months of age and over and to determine the appropriate treatment strategy. Method We performed a retrospective review of 3834 patients registered with the Japanese Society of Pediatric Oncology and Japanese Society of Pediatric Surgeons between 1980 and 1998. Results The rates of stage 4s patients were 10.7%, 6.3% and 3.3% in patients of ⩽11 months of age, from ⩾12 to ⩽17 months of age, ⩾18 months of age, respectively. The 5 year event-free survival rates were 89.4%, 100% and 53.1%, respectively. The rates of MYCN amplification and unfavourable histology were smaller in stage 4s groups than stage 4 groups in all ages. Conclusion In the children 12 months of age and older, stage 4s cases are markedly different from stage 4 cases in regard to the clinical features and prognosis. The prognosis of stage 4s cases from ⩾12 to ⩽17 months of age is excellent. The concept of stage MS appears to be appropriate.