State of the art and future prospects in the management of neuroendocrine tumors.

Neuroendocrine gastroenteropancreatic tumors are rather rare neoplasms with an incidence of 1-2 cases per 100,000 people. They show rather varying tumor biology and present sometimes distinct clinical symptoms such as flushing, diarrhoea, hypoglycemia and gastric ulcers. The biochemical diagnosis is today significantly improved by the introduction of chromogranin A as a general tumor marker, which is also useful in histopathology. Today the localization procedures include somatostatin receptor scintigraphy as the primary investigation together with CT or ultrasonography. The basis for treatment of neuroendocrine GEP tumors is not only a curative intent but merely amelioration of clinical symptoms, abrogation of tumor growth, maintaining and improvement of quality of life. Surgery has always to be considered in the treatment of neuroendocrine GEP tumors. It can be performed whenever during the course of the disease but it may be more productive in earlier stages. Liver dearterialization procedures can furthermore reduce the tumor masses in liver together with laser treatment or radiofrequency therapy. The medical treatment includes cytotoxic agents, alpha interferons and somatostatin analogues. Somatostatin analogues will always be combined with the other two alternatives to reduce clinical symptoms. Chemotherapy is particularly useful for patients with more aggressive tumors with high proliferation capacity, whereas alpha interferon is beneficial in classical midgut carcinoids with low proliferation capacity. Quite recently somatostatin based radioactive tumor targeted treatment has evolved with preliminary promising data but further studies are needed to deliniate its future role in the treatment of neuroendocrine tumors in patients.