In a neoadjuvant paclitaxel, trastuzumab, carboplatin combination (PTC) trial (GSE41656), TFF3 gene expression was observed to be significantly higher in non-complete responders (non-CR) of the combination of trastuzumab and chemotherapy treatment as compared to complete responders (CR) among both HER2+/ER+ and HER2+/ER- breast cancer patients (Supplementary Figure 6). This evidence concerns the gene ESR1 and breast cancer.