It was found that the rate of pathological complete remission in the HR-positive subgroup of HER2 low-expression breast cancers was significantly lower than that of HER2-0 breast cancers (p=0.024) (Table 2), HER2 low-expression breast cancers were histologically more poorly graded and had lower Ki-67 proliferation indices (20). The gene discussed is ERBB2; the disease is breast cancer.