Neuroendocrine tumours.

Neuroendocrine tumours are a heterogeneous group including, for example, carcinoid, gastroenteropancreatic neuroendocrine tumours, pituitary tumours, medullary carcinoma of the thyroid and phaeochromocytomas. They have attracted much attention in recent years, both because they are relatively easy to palliate and because they have indicated the chronic effect of the particular hormone elevated. As neuroendocrine phenotypes became better understood, the definition of neuroendocrine cells changed and is now accepted as referring to cells with neurotransmitter, neuromodulator or neuropeptide hormone production, dense-core secretory granules, and the absence of axons and synapses. Neuroendocrine markers, particularly chromogranin A, are invaluable diagnostically. Study of several neuroendocrine tumours has revealed a genetic etiology, and techniques such as genetic screening have allowed risk stratification and prevention of morbidity in patients carrying the particular mutation. Pharmacological therapy for these often slow-growing tumours, e.g. with somatostatin analogues, has dramatically improved symptom control, and radiolabelled somatostatin analogues offer targeted therapy for metastatic or inoperable disease. In this review, the diagnosis and management of patients with carcinoid, gut neuroendocrine tumours, multiple endocrine neoplasia types 1 and 2, and isolated phaeochromocytoma are evaluated.