Optimization of molecular radiotherapy with [131I]-meta Iodobenzylguanidine for high-risk neuroblastoma.

Molecular radiotherapy with [131I]-meta Iodobenzylguanidine ([131I]-mIBG) for neuroblastoma has been in clinical use for nearly 30 years. In this time, its role has changed from being an exclusively palliative treatment to one where the intent of treatment is often curative. To achieve this, the treatment has been brought forward from the relapse setting, to the beginning as induction therapy, as a possibility for salvage of those with chemo-refractory disease or as part of consolidation schedules. With the routine use of hemopoietic support, higher than previously standard administered activities are now commonly used. Other attempts to improve outcomes include the concomitant use of chemotherapy and radiation sensitisers and novel formulations such as no-carrier added [131I]-mIBG. Unfortunately, none of these strategies has been evaluated in a randomized controlled trial, so whether the theoretical benefits of these innovative approaches are seen clinically remains a matter of conjecture. Despite the prevalent belief in using higher administered activities, dosimetry has been under-used, hampering the ability to detect the benefit of this strategy. To properly evaluate concepts aiming at the optimisation of molecular radiotherapy with [131I]-mIBG for high-risk neuroblastoma, careful dosimetry in well-designed randomized clinical trials is essential. Only in this way will it be possible for [131I]-mIBG to be used to its best advantage in the complex multimodality treatment schedules required for high-risk neuroblastoma.