1. Department of Health and Society, Linköping University, S-S81 83 Linköping, Sweden
2. Department of Cancer Epidemiology, Radiumhemmet, Karolinska Hospital, S-171 76 Stockholm, Sweden and the Finnish Cancer Registry, SF-00170. Helsinki, Finland
3. Oncologic Centre, Umeå, University Hospital, S-901 85 Umeå, Sweden
4. Oncologic Centre, Linköping University Hospital, S-581 85 Linköping, Sweden
5. Mammography Department, Gävle Hospital, S-801 87 Gävle, Sweden
6. Oncologic Centre, Radiumhemmet, Karolinska Hospital, S171 76 Stockholm, Sweden