E. Senkus1, S. Kyriakides2, F. Penault-Llorca3,4, P. Poortmans5, A. Thompson6, S. Zackrisson7 & F. Cardoso8,9, on behalf of the ESMO Guidelines Working Group* Department of Oncology and Radiotherapy, Medical University of Gdansk, Gdansk, Poland; Europa Donna Cyprus, Nicosia, Cyprus; Department of Pathology, Centre Jean Perrin, Clermont-Ferrand; EA 4677 Universite d’Auvergne, Clermont-Ferrand, France; Institute Verbeeten, Tilburg, The Netherlands; Dundee Cancer Centre, University of Dundee, Dundee, UK; Diagnostic Radiology, Lund University, Malmo, Sweden; European School of Oncology, Milan, Italy; Breast Cancer Unit, Champalimaud Centre Center, Lisbon, Portugal