MEGA had full access to all data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Agree

with the manuscript’s results and conclusions: MEGA BJC EB JG GKR VB. Designed the experiments/the study: MEGA BJC EB JG GKR VB. Analysed the data: MEGA BJC. Collected data/did experiments for the study: VB EB. Enrolled patients: VB EB. Wrote the first draft of the paper: MEGA. Contributed to the writing of the paper: BJC EB JG GKR VB. Co-principal investigators of the Million Women Study: VB JG GKR. The authors have no competing interests Enzalutamide cost to declare. We thank the women who participated in the Million Women Study, the NHS Breast Screening Centre collaborators, and the steering committee of the Million Women Study (see below). We also thank the Information and Statistics Division in Scotland and the Information Centre for Health and Social Care and Northgate Solutions in England for the hospital admission data.

Funding: The Million Women Study is funded by LDK378 cost Cancer Research UK, the Medical Research Council, and the NHS Breast Screening Programme. The researchers act independently of the funders. Steering Committee: Joan Austoker, Emily Banks, Valerie Beral, Judith Church, Ruth English, Jane Baricitinib Green, Julietta Patnick, Richard Peto, Gillian Reeves, Martin Vessey, and Matthew Wallis. NHS Breast Screening Centres collaborating in the Million Women Study (in alphabetical order): Avon, Aylesbury, Barnsley, Basingstoke, Bedfordshire & Hertfordshire, Cambridge & Huntingdon, Chelmsford & Colchester, Chester, Cornwall, Crewe, Cumbria, Doncaster, Dorset, East Berkshire, East Cheshire, East Devon, East of Scotland, East Suffolk, East Sussex, Gateshead, Gloucestershire,

Great Yarmouth, Hereford & Worcester, Kent (Canterbury, Rochester, Maidstone), Kings Lynn, Leicestershire, Liverpool, Manchester, Milton Keynes, Newcastle, North Birmingham, North East Scotland, North Lancashire, North Middlesex, North Nottingham, North of Scotland, North Tees, North Yorkshire, Nottingham, Oxford, Portsmouth, Rotherham, Sheffield, Shropshire, Somerset, South Birmingham, South East Scotland, South East Staffordshire, South Derbyshire, South Essex, South Lancashire, South West Scotland, Surrey, Warrington Halton St Helens & Knowsley, Warwickshire Solihull & Coventry, West Berkshire, West Devon, West London, West Suffolk, West Sussex, Wiltshire, Winchester, Wirral and Wycombe.