[Treatment of malignant pheochromocytoma by 131-I-metaiodobenzylguanidine].

Twelve patients (2 with only bone metastases, 3 with only soft tissues metastases and 7 with bone and soft tissues metastases) were treated with 131-I-MIBG (specific activity: 20 mCi/mg), 100 to 200 mCi every 3-6 months. A dosimetric study was carried out before each administration. The follow-up ranged from 6 to 24 months and the number of doses ranged from 1 to 8, with 1.85-9 GBq per administration and a cumulative activity of 1.85-62. 2 GBq according to patients. The cumulative absorbed activity ranged from 850 to 9700 cGy. The following side effects were observed: a bone marrow hypoplasia (1 patient) and a transient increase in catecholamines (3 patients). The treatment was successful in 7 patients (3 with soft tissue metastases, 3 with bone and soft tissue metastases and one with bone metastases). This success consisted in clinical improvement and a decrease greater than 50% of hormonal values in the 7 patients and a decrease greater than 50% of tumoral masses in only 3 patients. No complete remission was obtained at this stage of the study. The disease recurred in 1 patient after a year of partial remission. There was no clear-cut relation between the number of doses and the results. This study shows that 131-I-MIBG can give encouraging though limited results.