In order to investigate how the gene-expression profiles of triple-negative tumors is related to basal-like tumors when analysed together with ER-, PR- and/or HER2-positive tumors, we performed hierarchical cluster analysis with the 97 triple-negative tumors combined with 102 invasive breast carcinomas, that were not selected based on their triple-negative status, using the 293 intrinsic-gene list [3] (Figure 1 and Additional file 1). This evidence concerns the gene ESR1 and invasive breast carcinoma.