A pCR is a surrogate end point that is a marker for improved disease-free and overall survival.4,6 The likelihood of achieving pCR is largely based on breast cancer subtype (clinically defined by immunohistochemical surrogates of estrogen receptor, progesterone receptor, and ERBB2 (formerly HER2 or HER2/neu) amplification, with ERBB2-positive and triple-negative subtypes having the highest likelihood of pCR of up to 66.2%7 and 37%,8 respectively. This evidence concerns the gene ERBB2 and breast cancer.