1. Department of Surgery, Stanford University School of Medicine, Stanford, California 94305
2. Department of Genetics, Norwegian Radium Hospital, University of Oslo, N-0310 Oslo, Norway
3. Department of Pathology, Stanford University School of Medicine, Stanford, California 94305
4. Department of Pathology, Norwegian Radium Hospital, University of Oslo, N-0310 Oslo, Norway
5. Department of Health Research and Policy and Statistics, Stanford University School of Medicine, Stanford, California 94305
6. Department of Surgery, Akershus University Hospital, 1474 Nordbyhagen, Norway
7. Department of Surgery, Ullevål University Hospital, N-0407 Oslo, Norway
8. Department of Genetics, Stanford University School of Medicine, Stanford, California 94305