PIK3CA and breast cancer: On the contrary, Cizkova et al. [59] found poorer DFS and OS in PIK3CA-mutant HER2+ BC treated with neoadjuvant and/or adjuvant trastuzumab, compared with wild type HER2+ BCs [59]; similarly, a detrimental impact of PIK3CA mutation on adjuvant treatment outcome in HER2+ BC has been reported by Jensen et al. [60].