Therefore, AJCC 8th Edition Cancer Staging Manual has updated with a prognostic stage (PS) group for breast cancer by incorporating traditional TNM anatomic parameters and additional biologic factors, including estrogen receptor (ER) and progesterone receptor (PR) status, HER2 status, tumor grade and Recurrence Scores (Oncotype Dx), which are known to have predictive and prognostic value [1, 2]. The gene discussed is ESR1; the disease is breast cancer.