[Gastroenteropancreatic neuroendocrine tumors : targeted diagnostics and therapy].

Gastroenteropancreatic neuroendocrine tumors (GEP-NET) are rare but an increase in incidence has been recognized worldwide. Approximately 70 % of NETs are localized in the gastrointestinal tract and in the pancreas, other locations are in the lungs (25 %) and rarely in the skin, urogenital tract and ovaries. Depending on the size, localization, grading (G1-G3) and production of hormones, the symptoms of patients can greatly vary. Outcome and survival of patients depend on the biological behavior and grading of the NET. Patients with a well differentiated G1 grade NET have a slow, sometimes also benign course over decades even with metastases in contrast to patients with G3 grade NETs. These tumors exhibit an aggressive behavior and patient survival is short. Liver and lymph node metastases are common (about 50 %) in GEP-NETs even at the initial diagnosis. The 5-year and 10-year survival of patients with GEP-NETs is increasing (currently approximately 80 % and 60 %, respectively), especially when a multidisciplinary team (e.g. surgery, endocrinology, oncology, nuclear medicine and gastroenterology) manages GEP-NET patients.