1. Medical Faculty, University of Zurich, Pestalozzistrasse 3, CH-8032 Zurich, Switzerland
2. Division of Chronic Disease Epidemiology, Epidemiology, Biostatistics and Prevention Institute (EBPI), University of Zurich, Hirschengraben 84, CH-8001 Zurich, Switzerland
3. Division of Cancer Epidemiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, DE-69120 Heidelberg, Germany