ESR1 and breast cancer: The breast cancer size (P < 0.001), nuclear grade (P = 0.04), ER status (P < 0.001), and Ki67 index (P < 0.001) of breast cancer were higher in the LN metastasis group than in the LN non-metastasis group, and no significant difference was observed in age, histologic type, PgR status, or HER2 status between the groups.