 All NETs of both, gastrointestinal and pulmonary origin are included provided that patients have given informed consent. Data will be entered prospectively and anonymised in a specifically designed database. Contributing centres and general practitioners are visited by a study nurse, patient files are analysed and data is transferred to the database. In case of conflicting evidence, questions are resolved in collaboration with a review board of SwissNET. Evaluation of treatment modalities and patient outcomes e.g. mortality, hospitalisation rate will take place within regular time frames. 