131I-metaiodobenzylguanidine treatment in neuroblastoma: report of two cases.

Poor results with 131I-meta-iodobenzylguanidine (MIBG) therapy have been obtained in two children with stage IV neuroblastoma treated after partial surgery and unsatisfactory combination chemotherapy. Both patients' response to treatment (four and three 1-month-spaced courses, respectively; cumulative administration of 11.9 and 9.2 GBq) has been characterized by a low isotope concentration in the primary tumor and in the multiple bone metastases and by bone marrow uptake with final severe hematological toxicity. A slight decrease in the primary tumor's volume was observed in one patient at a cumulative dose of 85 Gy; there was no change in the other's at 42 Gy. At an initial, greater isotope concentration delivering 103 Gy, some bone metastases displayed a sharp decrease in uptake that persisted in the successive courses. For both patients a progressive spreading of new tumor localisation in the bones and finally in the soft tissues was observed.