Canadian research indicates that the overall performance of screening mammography is improved when screening is done in large centres and when, in those centres, mammograms are read by radiologists who interpret a large number of films.

Isabelle Théberge and colleagues examined the relation between the volume of screeningmammography and rates of detection of breast cancer and of false positive readings in theQuebec breast cancer screening programme (CMAJ 2005;172:195-9). The study looked at data on 307 314 asymptomatic women aged 50 to 69 years who were screened between May 1998 and December 2000. Each screening included four radiographic …