The introduction of targeted therapies and optimized combinations of chemotherapeutics, coupled with better surveillance, have increased survival, especially for patients with estrogen receptor (ER) and progesterone receptor (PR) or human epidermal growth factor receptor 2 (HER2) positive primary breast cancer; however, the significance of these therapeutic and technological advances for metastatic breast cancer (MBC) survival remains controversial [2–6]. This evidence concerns the gene ESR1 and breast carcinoma.