In a prospective study of 138 women with human epidermal growth factor receptor 2–positive breast cancer who were treated with trastuzumab, N‐terminal pro‐B‐type natriuretic peptide levels at baseline and during follow‐up were associated with development of cardiotoxicity, defined as LVEF <45% or an absolute decline in LVEF >10% or the occurrence of a clinical cardiac event.50 This evidence concerns the gene ERBB2 and breast carcinoma.