Iodine-131 metaiodobenzylguanidine is an effective treatment for malignant pheochromocytoma and paraganglioma

Introduction. Iodine 131-meta-iodobenzylguanidine (I-131-MIBG) has been applied to the palliative treatment Of metastatic pheochromocytoma in small studies. We report our institutional experience for the treatment Of metastatic pheochromocytoma and paraganglioma. Methods. We performed a retrospective review of 33 patients with metastatic pheochromocytoma (n = 22) and paraganglioma (n = 11) treated at our institution with I-131-MIBG over a 10-year period. Results. Patients received a mean dose of 388 +/- 131 mCi I-131-MIBG. Median survival after treatment was 4.7 years. Most patients experienced a symptomatic response leading to an improved survival (4.7 years vs 1.8 years, P < . 01). Patients with a measurable hormone response demonstrated an increased survival in comparison to those with no response (4.7 years vs 2.6 years, P = .01). Patients who received a high dose (>500 mCi) as their initial therapy also had improved survival (3.8 years vs 2.8 years, P = .02). Conclusion. These data support I-131-MIBG treatment for select patients with metastatic pheochromocytoma. In our experience, prolonged survival was best predicted by symptomatic and hormone response to I-131-MIBG treatment. An initial dose of 500 mCi may be optimal. The benefit of I-131-MIBG treatment for metastatic pheochromocytoma must also be weighed against its side effects.