Preliminary results of [131]metaiodobenzylguanidine treatment in metastatic malignant pheochromocytoma.

The poor results of traditional therapy (for purposes of recovery or palliation) in malignant pheochromocytoma and the well proven uptake of [131I]metaiodobenzylguanidine (131I-MIBG) shown by these tumors, induced us to evaluate the clinical usefulness of radiometabolic therapy with 131I-MIBG. Four patients with malignant pheochromocytoma were subjected to 131I-MIBG therapy, between 1987 and 1991, in our department. They all were in an advanced stage of the disease and showed severe symptoms and poor reaction to traditional therapy. The cumulative activity given was 7.4-22.2 GBq. All patients demonstrated transient subjective improvement; in addition, both biochemical and haemodynamic parameters ameliorated. Two patients showed a reduction in the size and number of metastases seen on scintigraphy. One patient died due to progression of the disease. Three patients are still alive and in good condition. No remarkable early or late side-effects were reported. We suggest that 131I-MIBG radiometabolic therapy in advanced-stage malignant pheochromocytoma could be useful in reducing symptoms. Further investigation might show whether a greater reduction in the size of the tumor could be achieved using different therapeutic schedules or by treating the disease in its earlier stages.