Clinical biomarkers in BC cores showed particularly strong reproducibility; specifically, for ER, ICC = 0.88 (95%CI: 0.81–0.92); for HER2, ICC = 0.92 (95%CI: 0.88–0.95) and for Ki67, ICC = 0.63 (95%CI: 0.49–0.75). This evidence concerns the gene MKI67 and breast cancer.