Acknowledgments
We acknowledge support from the MRC (G1000718 and K006215), Breakthough Breast Cancer, and NHS funding to the NIHR Biomedical Research Centre. We thank the Breast Cancer Association Consortium (BCAC) for access to the data published in Johnson et al.15 BCAC is funded by Cancer Research UK (C1287/A10118, C1287/A12014) and by the European Community’s Seventh Framework Programme under grant agreement number 223175 (HEALTH-F2-2009-223175) (COGS).