1. Institute of General Practice, Goethe University Frankfurt am Main, Frankfurt, Germany
2. Institute of General Practice and Evidence-Based Health Services Research, Medical University Graz, Graz, Austria
3. Institute of Medical Biostatistics, Epidemiology and Informatics (IMBEI), Mainz, Germany
4. German Cancer Consortium (DKTK), Partner Site Frankfurt/Mainz, Germany
5. German Cancer Research Center (DKFZ), Heidelberg, Germany