Developments in Digestive Tract Neuroendocrine Tumours and Pheochromocytomas/Paragangliomas – A Narrative Review

Abstract

Digestive neuroendocrine tumours (carcinoids) derive from serotonin-producing enterochromaffin cells. Biochemical screening (and follow-up) is performed with measurements of 5-hydroxyindoloacetic acid in urine. Other markers are also useful. Most digestive neuroendocrine tumours are better localised with functional imaging, i.e. nuclear medicine, compared with other modalities. The treatment of choice is surgical; non-resectable tumours are treated with somatostatin analogues (unlabelled and for more advanced disease radiolabelled) or chemotherapy. Most pheochromocytomas/paragangliomas are sporadic, however, and genetically caused tumours are much more common than previously thought. Biochemical proof of disease is best carried out with measurement of plasma metadrenaline. Imaging with computed tomography or magnetic resonance imaging (MRI) should be followed by functional imaging. Chromaffin tumour-specific methods are preferred.18F-fluoro-deoxyglucose positron emission tomography (18F-DOPA PET) should be used in patients with succinate-dehydrogenase-B-related metastatic pheochromocytoma/paraganglioma.18F-DOPA PET may become a modality of choice for the localisation of head and neck paragangliomas. If possible, treatment is surgical. For non-operable disease, other options are available and new drugs are under investigation or in clinical trials.