MKI67 and breast cancer: In HER2-nonamplified BC with high Ki-67 index, the 8-year OS and BCSS of HER2-low-positive BC was significantly better than HER2-0 BC (91% vs. 88%, p=0.026, Figure 4(c); 94% vs. 91%, p=0.052Figure 4(d)), while no significant difference of RFS could be observed between the two cohorts (88% vs. 86%, p=0.17).