1 Manuscript title: Multifocal breast cancers are more prevalent in BRCA2 versus BRCA1 mutation carriers Running title: Multifocality in BRCA-associated breast cancer Author list: Alan David McCrorie 1 , Susannah Ashfield 1,2 Colin Mcilmunn 1 , Patrick J. Morrison 3 , Clinton Boyd 4 , Kienan I. Savage ±1 , Stuart Andrew McIntosh ±1 * [1] Centre for Cancer Research & Cell Biology, Queen’s University Belfast, 97 Lisburn Road, Belfast, BT9 7AE [2] University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, Cambridge, CB2 0SP [3] Northern Ireland Regional Genetics Centre, Belfast Health and Social Care Trust, 51 Lisburn Road, Belfast, BT9 7AB [4] Institute of Pathology, Royal Victoria Hospital, Belfast, BT12 6BA ± contributed equally *Corresponding author: Stuart McIntosh Clinical Senior Lecturer in Surgical Oncology Centre for Cancer Research and Cell Biology Queen’s University Belfast 97 Lisburn Road Belfast BT9 7AE. Tel: 02890972986 Email: s.mcintosh@qub.ac.uk Conflict of interest statement: The authors declare no conflicts of interest. Word count: 1496 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted September 13, 2019. . https://doi.org/10.1101/19006478 doi: medRxiv preprint