1. Departement of Anesthesiology and Intensive Care Medicine, Hannover Medical School, 30625 Hannover, Germany
2. Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, 30625 Hannover, Germany
3. Centre for Biometry, Medical Informatics and Medical Technology, Institute for Biometry, Hannover Medical School, 30625 Hannover, Germany
4. Tumour Centre Hannover, Hannover Medical School, 30625 Hannover, Germany
5. Gastrointestinal Malignancies, National Cancer Institute, Bethesda, MD 20892-8322, USA