The therapeutic options for early breast cancer (eBC) have been improved in the last few years and the greater use of neoadjuvant therapy (NAT), in particular for HER2-positive and TN BC [77,78], led to consider residual disease as a risk factor, in addition to classic prognostic elements such as tumor histology, grade, stage, hormone receptors, and HER2 expression, in the choice of the best adjuvant treatment [79,80]. The gene discussed is ERBB2; the disease is breast cancer.