1. Department of Obstetrics and Gynecology, Akershus University Hospital, P.O. Box 1000, N-1478 Lørenskog, Norway
2. Department of Public Health and Caring Sciences, Uppsala University, P.O. Box 564, SE-75122 Uppsala, Sweden
3. Department of Mammography Screening, Cancer Registry of Norway, P.O. Box 5313, Majorstuen, N-0304 Oslo, Norway
4. Department of Surgical Sciences, Uppsala University, P.O. Box 564, SE-75122 Uppsala, Sweden
5. Institute of Clinical Medicine, Campus Ahus, University of Oslo, P.O. Box 1000, N-1478 Lørenskog, Norway