MKI67 and breast cancer: In this study, 64.9% of the patients exhibited HER2-low, and we compared the clinical case characteristics of HER2-low and HER2-zero HR-negative BC patients, which suggested that compared to HER2-zero patients, HER2-low patients were older (p = 0.035), had a later clinical N-stage (p = 0.001), and had higher Ki67 expression (p = 0.012), but histological grading was more (p < 0.001).