Our results showed that age (HR = 1.04341252, P = 3.17E-08), TNM stage (HR = 2.39546349, P = 8.93E-13), ER (HR = 0.58848779, P = 0.01866529), and high KIF2C expression (HR = 1.60169321, P = 0.02724886) were independent prognostic factors for OS in breast cancer patients (Tables 2 and Supplementary Fig. 1B). Here, ESR1 is linked to breast cancer.