Biology, diagnosis, and treatment of neuroendocrine tumors of the gastrointestinal tract.

Neuroendocrine tumors constitute only 2% of all malignant gastrointestinal tumors but have attracted a lot of scientific interest during the past decade. These tumors are excellent models for studies of new diagnostic and therapeutic tools. During the past year, major breakthroughs have been made in the areas of both diagnosis and therapy, but in particular, the development of somatostatin receptor scintigraphy and positron emission tomography have been major contributions to the diagnosis, localization, and tumor biology. The introduction of somatostatin analogues and interferons alone, or in combinations, have further improved the quality-of-life for patients with these tumors and probably has also prolonged the overall survival. Recent data on the expression of various growth factors, receptors, oncogenes, and tumor-suppressor genes have increased our understanding about the tumor biology. However, we are just at the beginning and to further improve the clinical management of these patients we have to put more effort into areas of molecular genetics and growth regulation of these tumors. This review discusses the recent developments in biology, diagnosis, and treatment of gut neuroendocrine tumors.