IHC analyses of the estrogen receptor (ER), the progesterone receptor (PgR), human epidermal growth factor receptor type 2 (HER2), and the Ki-67 index were used as surrogates for genetic profiling to determine breast cancer treatment strategies, which include neoadjuvant or adjuvant systemic therapy to reduce the risk of recurrence, to prolong life and maintain quality of life. The gene discussed is ESR1; the disease is breast carcinoma.