Update on magnetic resonance screening and the MARIBS trial

Genetically predisposed women often develop breast cancer when young and when dense breast tissue reduces the sensitivity of X-ray mammography (XRM). A UK multicentre study comparing the performance of contrast enhanced magnetic resonance imaging (CE MRI) with XRM in these women commenced in 1997 and reported 2005. In this multicentre study, CE MRI was significantly more sensitive than XRM in cancer detection for the entire cohort, but especially in the subgroup of BRCA1 carriers. Specificity for both procedures was acceptable. Despite a high proportion of Grade 3 tumours, the tumours were small and few women were node-positive. These findings resemble the results from the Netherlands six-centre MRISC study and a single-centre study from Toronto. These studies give support for a policy of annual screening combining CE MRI and XRM, which would detect most tumours in this risk group. These studies show evidence of effective small cancer detection, but do not have sufficient power to show whether mortality is reduced, for which there is no current evidence.