Thyroid and Hepatic Function After High-Dose 131I-Metaiodobenzylguanidine (131I-MIBG) Therapy for Neuroblastoma

Background. I-131-Metaiodobenzylguanidine (I-131-MIBG) provides targeted radiotherapy for children with neuroblastoma, malignancy of the sympathetic nervous system. Dissociated radioactive iodide may concentrate in the thyroid, and I-131-MIBG is concentrated in the liver after I-131-MIBG therapy. The aim of our study was to analyze the effects of I-131-MIBG therapy on thyroid and liver function. Procedure. Pre- and post-therapy thyroid and liver functions were reviewed in a total of 194 neuroblastoma patients treated with I-131-MIBG therapy. The cumulative incidence over time was estimated for both thyroid and liver toxicities. The relationship to cumulative dose/kg, number of treatments, time from treatment to follow-up, sex, and patient age was examined. Results. In patients who presented with Grade 0 or 1 thyroid toxicity at baseline, 12 +/- 4% experienced onset of or worsening to Grade 2 hypothyroidism and one patient developed Grade 2 hyperthyroidism by 2 years after I-131-MIBG therapy. At 2 years post-I-131-MIBG therapy, 76 +/- 4% patients experienced onset or worsening of hepatic toxicity to any grade, and 23 +/- 5% experienced onset of or worsening to Grade 3 or 4 liver toxicity. Liver toxicity was usually transient asymptomatic transaminase elevation, frequently confounded by disease progression and other therapies. Conclusion. The prophylactic regimen of potassium iodide and potassium perchlorate with I-131-MIBG therapy resulted in a low rate of significant hypothyroidism. Liver abnormalities following I-131-MIBG therapy were primarily reversible and did not result in late toxicity. I-131-MIBG therapy is a promising treatment for children with relapsed neuroblastoma with a relatively low rate of symptomatic thyroid or hepatic dysfunction. Pediatr Blood Cancer 2011;56:191-201. (C) 2010 Wiley-Liss, Inc.