[1] Wolfson Inst Prevent Med, Canc Res UK Ctr Epidemiol Math & Stat, London, England
[2] Univ Copenhagen, Inst Publ Hlth, DK-1168 Copenhagen, Denmark
[3] Falun Cent Hosp, Dept Mammog, Falun, Sweden
[4] Breast Test Wales, Cardiff, Wales
[5] Iceland Canc Registry, Reykjavik, Iceland