Is there a benefit of 131I-MIBG therapy in the treatment of children with stage 4 neuroblastoma?

SummaryAim: 131I-meta-iodobenzylguanidine (131I-MIBG) therapy has been used in neuroblastoma treatment for many years but its value in high intensive first line treatment protocols is not exactly known. Patients, methods: Stage 4 neuroblastoma patients >1 year with 123I-MIBG positive residual disease (primary tumour and/or metastasis) after complete induction chemotherapy according to the German neuroblastoma trial NB97 were retrospectively analyzed. Results: One-hundred-eleven patients had 123I-MIBG positive residual disease after complete induction chemotherapy. Forty patients received 131I-MIBG therapy using a median activity of 0.44 GBq/kg body weight. By univariate analysis, patients who underwent 131I-MIBG therapy had a better 3-year event free survival (3-y-EFS 46±8%) and 3-year overall survival (3-y-OS 58±9%) than 71 patients without 131I-MIBG therapy (3-y-EFS 19±5%, p=0.003; 3-y-OS 43±6%, p=0.037). However, subgroup analysis of 66 patients who underwent high dose chemotherapy with autologous stem cell transplantation (ASCT) during treatment found a very similar outcome with 131I-MIBG therapy (3-y-EFS 49±9%, 3-y-OS 59±10%) and without 131I-MIBG therapy (3-y-EFS 33±9%, p=0.171; 3-y-OS 59±9%, p=0.285) due to the dominating effect of ASCT. By multivariate analysis, 131I-MIBG therapy had no impact on EFS (p=0.494) and OS (p=0.891). Only ASCT, external beam radiation therapy and MYCN amplification were important for EFS and OS. Conclusions: An independent advantage of I-131-MIBG therapy could not be proven in this retrospective analysis. The ongoing German Neuroblastoma Trial NB2004 will address the influence of 131I-MIBG therapy with emphasis on tumour dosimetry.