Neuroendocrine tumours

Neuroendocrine tumours can be divided into endocrine neoplasms occurring in the lungs, thymus, gastrointestinal tract and pancreas. Most neuroendocrine tumours are slowly growing neoplasms, but some of them are highly malignant and show an aggressive behaviour. A special feature of neuroendocrine tumours is the ability to produce peptides or hormones, for example, serotonin, histamine, ACTH, VIP, insulin, proinsulin, glucagon or calcitonin, thereby giving rise to disabling endocrine syndromes such as the carcinoid syndrome, an atypical carcinoid syndrome, ectopic Cushing's syndrome, the WDHA-syndrome, the insulinoma syndrome or the glucagonoma syndrome. The treatment of patients with neuroendocrine tumours consists of surgery, radiotherapy, biotherapy, chemotherapy and local ablative treatments such as liver embolization and radiofrequency ablation. Nearly all patients should be considered for surgery, which is the only curative treatment but may also be used for debulking of metastases. Radiotherapy may either be given as conventional radiotherapy, usually against bone or brain metastases, or as targeted irradiation therapy with ¹¹¹Indium-, ⁹⁰Yttrium- or ¹⁷⁷Lutetium-labelled somatostatin analogues. Biotherapy traditionally consists of alpha-interferon and somatostatin analogues, which may show antitumoural activity and relieve endocrine symptoms. Today, several new biological agents have been introduced such as tyrosine kinase inhibitors, mTOR inhibitors and antiangiogenic agents. Various chemotherapy combinations are used in patients with endocrine pancreatic tumours, lung and thymic carcinoids and in patients with highly aggressive neuroendocrine tumours. Most patients with neuroendocrine tumours have a relatively good prognosis with long expected survival, but the prognosis in patients with poorly differentiated neuroendocrine tumours is poor.