External Beam Radiotherapy in Advanced Pheochromocytoma and Paraganglioma: An Observation of a Rare Abscopal Effect.

Metastatic pheochromocytoma and paraganglioma are incurable, and effective treatment of systemic symptoms resulting from catecholamine excess and local symptoms from tumor growth are crucial to prolong survival and improve quality of life. We report the first case of metastatic pheochromocytoma wherein external beam radiotherapy (EBRT) demonstrated efficacy in both target and nontarget lesions, demonstrating the "abscopal effect." EBRT reduced tumor volume and catecholamine secretion and improved catecholamine excess-related complications, including glycemic control. EBRT is an effective treatment option for metastatic pheochromocytoma and paraganglioma because of its minimal invasiveness, safety, and potential for the rare abscopal effect.