MKI67 and breast cancer: Our results indicated that there was no significant survival difference between HER2-low-positive and HER2-0 tumors regardless of HR status (p > 0.05), while OS (p=0.026) and BCSS (p=0.052) of HER2-0 BC with high Ki-67 index were significantly poorer than that of HER2-low positive with high Ki-67, but not for RFS (p=0.17).