In the Immediate Preoperative Anastrozole, Tamoxifen, or Combined with Tamoxifen (IMPACT) neoadjuvant trial, BC cell proliferation was measured by Ki67 immunohistochemistry (IHC) and it was demonstrated that almost 40% of patients presented with a high correlation of a 5-years recurrence free survival (RFS) upon short term anti-E2 therapy (15). The gene discussed is MKI67; the disease is breast cancer.