1. Center of Clinical Epidemiology, Institute of Medical Informatics, Biometry and Epidemiology; University Hospital of Essen; Essen Germany
2. Department of Epidemiology, School of Public Health; Boston University; Boston Massachusetts
3. German Consortium for Translational Cancer Research (DKTK); Heidelberg Germany
4. Institute of Medical Informatics, Biometry and Epidemiology; University Hospital of Essen; Essen Germany