Thus, it is not surprising that assessing the expression of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor two (HER2) and proliferation remains the cornerstone of breast cancer diagnosis and treatment [2], although the well-known problems of accuracy and reproducibility which have necessitated the issuing of various guidelines [3–6], are still persistent [7]. The gene discussed is ESR1; the disease is breast cancer.