Tumor node metastasis, lymphovascular invasion, and grading, along with estrogen receptor (ER) and progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), and the proliferation index (Ki-67), are established prognostic and predictive markers employed in routine practice for the stratification of breast cancer patients [4,5,6,7]. The gene discussed is ERBB2; the disease is breast cancer.