[1] Univ London Queen Mary Coll, Wolfson Inst Prevent, Canc Res UK Dept Epidemiol Math & Stat, London EC1M 6BQ, England
[2] UCL, Dept Stat Sci, London WC1E 6BT, England
[3] Falun Cent Hosp, Dept Mammog, S-79182 Falun, Sweden
[4] Univ Hosp, Dept Radiol, S-58185 Linkoping, Sweden
[5] Univ Hosp, Mammog Dept, S-58185 Linkoping, Sweden
[6] Amer Canc Soc, Dept Canc Control, Atlanta, GA USA
[7] Natl Taiwan Univ, Inst Prevent Med, Taipei, Taiwan