ESR1 and breast cancer: Of the 65 histological sections of breast cancers, 29/65 showed nuclear positivity for Top 2 A. Node positive tumours 17/65 stained positive for Top 2 A. Stage I tumours 2/65, stage II tumours 12/65 and stage III 14/65 stained positive for Top 2 A. Among the HER2/neu-positive tumours, 22/65 stained for Top 2 A and among ER/PR-positive 9/65 cases were positive for Top 2 A. Triple-negative tumours 5/65 stained for Top 2 A.