Ultrahigh-risk group within the high-risk neuroblastoma category.

Children with high-risk neuroblastoma (NBL) constitute a heterogenous group, but little attention has been paid to further subdivision of the high-risk group. Although the current therapies including multiple high-dose consolidations have neared their efficacy and tolerability limits, alternative therapies are needed. We wanted to define an ultrahigh-risk group among high-risk NBL patients, to be potential candidates for novel therapies given up-front. Children with high-risk NBL (n=59) treated at a single institution during 1987 to 2010 were evaluated for upfront prognostic factors at diagnosis and response to induction therapy. The overall outcome was not different during 1987 to 1994 versus 1995 to 2010. Therapy consisted of induction chemotherapy, surgery, and high dose-consolidation (single, tandem, or triple) with autologous stem cell rescue, followed by local irradiation and cis-retinoic acid. MYCN amplification and bone metastases were powerful upfront prognostic factors, and a combination of these determined an ultrahigh-risk group with a 5-year event-free survival of 0.125±0.083. The combination of MYCN amplification and bone metastases overruled the intensity of the therapy given and remained the only significant predictor (P<0.019) in a multiple step-wise forward Cox regression analysis. We conclude that high-risk NBL patients can be categorized into prognostic subgroups based on MYCN status and bone metastases. MYCN amplification and bone metastases combined determined an ultrahigh-risk group of patients being suitable candidates for novel alternative therapies.