1. Department of Research, Cancer Registry of Norway, Oslo, Norway
2. Department of Cancer Genetics, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
3. Department of Oncology, Oslo University Hospital, Oslo, Norway
4. Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD, USA
5. Department of Epidemiology and Biostatistics, Imperial College London, London, UK