ESR1 and breast carcinoma: Data analysis from subgroups suggests that patients with hormone receptor (HR)‐positive, HER2‐positive tumors are less likely to achieve pCR than those with HR‐negative, HER2‐positive tumors, indicating that the interference of estrogen receptor (ER) and/or progesterone receptor (PR) signaling dampens effective control of HER2‐positive breast cancer.16