Cheang et al. [8] (2009) integrated Ki-67 expression as a prognostic factor into molecular typing, and their results showed Luminal B breast cancer patients with positive axillary lymph nodes (ER and/or PR positive, HER-2 positive, ≥14% Ki-67 positive cells) had a poorer 10-year recurrence free survival rate (64% vs. 47%, P<0.001) and a poorer overall survival rate (74% vs. 59%, P<0.001) when compared with Luminal A breast cancer patients (ER and/or PR positive, HER2 negative, <14% Ki-67 positive cells). This evidence concerns the gene ESR1 and breast cancer.