[1] Wolfson Inst Prevent Med, Canc Res UK Ctr Epidemiol Math & Stat, London WC1M 6BQ, England
[2] Dutch Canc Soc, Dept Pathol, Nijmegen, Netherlands
[3] Addenbrookes Hosp, Cambridge Breast Unit, Cambridge, England
[4] Univ Sydney, Sch Publ Hlth, Screening & Test Evaluat Program, Sydney, NSW 2006, Australia
[5] Univ Birmingham, W Midlands Breast Screening Qual Assurance Refere, Birmingham, W Midlands, England