Ity Nijmegen Medical Centre, Geert Grooteplein 28, Nijmegen, 6525 GA, The Netherlands Full list of author information is available at the end of the articleof breast cancers. Apart from breast epithelial tumor cells, ESR2 is also expressed in adjacent infiltrating lymphocytes, fibroblasts, and endothelial cells, all of which are known to influence tumor growth [3]. However, its precise role in bre