Multidisciplinary management of refractory insulinomas

Abstract

Insulinomas are predominantly benign (~90%), pancreatic neuroendocrine tumours characterized by hyperinsulinaemic hypoglycaemia. They usually present as a small (<2 cm), well-demarcated, solitary nodule that can arise in any part of the organ. Treatment for sporadic insulinomas is generally aimed at curative surgical resection with special consideration in genetic syndromes. Patients with significant hypoglycaemia can pose a difficult management challenge. In isolated cases where the patient is not medically fit for surgery or with metastatic spread, other treatment options are employed. Medical therapy with diazoxide or somatostatin analogues is commonly used first line for symptom control, albeit with variable efficacy. Other medical options are emerging, including newer targeted biological therapies, including everolimus (an mTOR inhibitor), sunitinib (a tyrosine kinase inhibitor) and pasireotide, a multisomatostatin receptor ligand. Pasireotide and everolimus both cause hyperglycaemia by physiological mechanisms synergistic with its antitumour/antiproliferative effects. Minimally invasive treatment modalities such as ethanol ablation are available in selected cases (particularly in patients unfit for surgery), peptide receptor radionuclide therapy (PRRT) can effectively control tumour growth or provide symptomatic benefit in metastatic disease, while cytotoxic chemotherapy can be used in patients with higher-grade tumours. This review considers the developments in the medical and other nonsurgical management options for cases refractory to standard medical management. Early referral to a dedicated neuroendocrine multidisciplinary team is critical considering the array of medical, oncological, interventional radiological and nuclear medical options. We discuss the evolving armamentarium for insulinomas when standard medical therapy fails.

Keywords: ablation; everolimus; insulinoma; neuroendocrine tumours; pasireotide; peptide receptor radionuclide therapy; sunitinib.