ESR1 and breast neoplasm: Yet an examination of the biomedical literature reveals a relative lack of molecular genomic characterization of brain metastases [5], which could lead to effective therapeutic interventions and better patient outcomes as evidenced by advancements in therapies guided by molecular targets to treat primary breast tumors, e.g., drugs targeting estrogen receptor-alpha (ERα) or the epidermal growth factor receptor ERBB2/HER2 [6].