ERBB2 and neoplasm: Nevertheless, in the study by Moura Leite et al., median Ki67 was 70% in HER2-low groups vs. 60% in HER2-0 (p = 0.80), and the proportion of grade III tumours did not differ between the two groups (67.3% in HER2-low vs. 67.8%, p = 0.91).