Treatment of children over the age of one year with unresectable localised neuroblastoma without MYCN amplification: Results of the SIOPEN study

Background In children older than 1 year with localised unresectable neuroblastoma (NB), treatment strategies are heterogeneous according to the national groups. The objective of this phase III non-randomised study was to evaluate the efficacy of conventional chemotherapy followed by surgery. Patients and methods In the presence of surgical risk factors (SRF), six courses of chemotherapy alternating Carboplatin–Etoposide and Vincristin–Cyclophosphamide–Doxorubicin were given, and surgical resection was attempted after four. Survival analyses were performed using an intention-to-treat approach. The main objective was to achieve a 5-year survival over 80%. Results Out of 191 registered children, 160 were evaluable. There were 62.5% older than 18 months and 52.5% had unfavourable histology according to International Neuroblastoma Pathology Classification (INPC). Chemotherapy reduced the number of SRFs by one third. Delayed surgery was attempted in 86.3% of patients and was complete or nearly complete in 74%. The 5-year EFS and OS were 76.4% and 87.6% respectively, with significant better results for patients younger than 18 months or with favourable histology. Conclusion This strategy provides encouraging results in children older than 1 year or 12 months with localised unresectable NB without MYCN amplification. However, in children older than 18 months and with unfavourable histology, additional treatment is recommended.