Second malignancies in children with neuroblastoma after combined treatment with 131I-metaiodobenzylguanidine

BACKGROUND. 131I-metaiodobenzylguanidine (131I-MIBG) is selectively taken up by cells of neural crest origin, allowing targeted radiotherapy of tumors such as neuroblastoma (NB) and pheochromocytoma. Radiotherapy may provide additional benefits in the treatment of NB, with moderate side effects such as hematologic and thyroid toxicity. However, with longer follow-up, other complications might occur. We describe our experience with second cancers occurring in children treated with 131I-MIBG and chemotherapy. METHODS. The clinical records of 119 consecutive NB cases treated with 131I-MIBG at a single institution between 1984 and 2001 were reviewed for the occurrence of a second malignant neoplasm (SMN). RESULTS. Overall, five cases of SMN occurred in the study patients. In particular, two cases of myeloid leukemia, one of angiomatous fibrous histiocytoma, one of malignant schwannoma, and one case of rhabdomyosarcoma were detected. The schwannoma and the rhabdomyosarcoma developed within the residual neuroblastic mass after first-line therapy. CONCLUSIONS. Should 131I-MIBG treatment become more broadly employed in the therapeutic strategy for neuroblastoma, the risk of second cancer will have to be taken into consideration. The organization of an international registry of subjects treated with 131I-MIBG might better define the frequency and features of second malignancies following this radiometabolic approach.