Metaiodobenzylguanidine and somatostatin in oncology: role in the management of neural crest tumours.

Two recently developed radiopharmaceuticals, iodine-131 metaiodobenzylguanidine (MIBG) and indium-111 pentetreotide, are currently being used for the diagnosis and therapy of neural crest tumours by interaction with the characteristic features of these tumours, such as an active uptake-1 mechanism at the cell membrane and the presence of vesicles or neurosecretory granules in the cytoplasm and of specific receptors at the cell membrane. This review focuses on the role of MIBG and somatostatin analogues in the management of neural crest tumours. A number of aspects of both tracers are compared and the cumulative results are reviewed. Other uses of these radiopharmaceuticals are mentioned. It is concluded that both 111In-pentetreotide and 123I/131I-MIBG are sensitive indicators of neural crest tumours, and have a complementary role. Unlike MIBG, 111In-pentetreotide is not specific for neural crest tumours, as scintigraphy is also positive in many other tumours, granulomas and autoimmune diseases. 131I-MIBG is effective in the therapy of several neural crest tumours; the biodistribution of 111In-pentetreotide at present does not allow radionuclide therapy using a beta-emitting label. However, as an indicator of somatostatin receptors, 111In-pentetreotide scintigraphy may be a predictor of response to palliative treatment with unlabelled octreotide. Recommendations for the use of these procedures are given.