Treatment of malignant pheochromocytoma with [131I]metaiodobenzylguanidine: a French multicenter study.

Six Medical Centers in France were involved in a prospective study evaluating the efficacy of [131I]metaiodobenzylguanidine (131I-MIBG) in the treatment of malignant pheochromocytoma. Fifteen patients aged from 28 to 75 years bearing tumor sites demonstrating a good MIBG uptake were included in this study. Catecholamines were elevated in 13/14 cases, VMA in 9/14 and metanephrines in 13/14. Two to 11 therapeutic activities of 131I-MIBG were administered, with a mean number of therapeutic doses per patient of 4 and a mean single activity of 4.7 GBq (range 2.9 to 9.25 GBq). Seven patients were alive, and seven patients died 6 to 29 months after their first MIBG administration (mean follow-up of 36 months); 1 patient was lost to follow-up. Two patients had a partial tumor response only, 4 had a hormonal response only, and 3 had both a partial tumor response and a hormonal response (complete in 2 cases). Six patients did not respond to the treatment, 4 of them died. Of the 9 responding patients, 4 relapsed, 3 of whom died subsequently. Haematological toxicity was always transient and mild, except in 1 case.