Effect of mitotane in patients with ectopic adrenocorticotropic hormone syndrome caused by advanced pancreatic neuroendocrine tumors: a case series and review of the literature

Ectopic adrenocorticotropic hormone syndrome (EAS) is a rare condition caused by pancreatic neuroendocrine tumors (p-NETs). The severe hypercortisolemia that characterizes EAS is associated with a poor prognosis and survival. Mitotane is the only adrenolytic drug approved by the Food and Drug Administration and is often used to treat adrenocortical carcinoma. Combination therapy with mitotane and other adrenal steroidogenesis inhibitors is common for patients with Cushing's syndrome (CS). Here, we describe three patients who developed EAS secondary to the liver metastasis of p-NETs. All three rapidly developed hypercortisolemia but no typical features of CS. They underwent anti-tumor and mitotane therapy, which rapidly reduced their blood cortisol concentrations and ameliorated their symptoms. Their hypercortisolemia was controlled long term using a low dose of mitotane. The principal adverse effects were a slight loss of appetite and occasional dizziness, and there were no severe adverse effects. Importantly, even when the tumor progressed, the patients' circulating cortisol concentrations remained within the normal range. In summary, the present case series suggests that mitotane could be used to treat hypercortisolemia in patients with EAS caused by advanced p-NETs, in the absence of significant adverse effects.