Patients with 1) ≥ 4 axillary lymph node metastases or 2) 1–3 axillary lymph node metastases with a tumor diameter ≥ 5 cm or histological grade 3 were included in cohort 1; and those with 1–3 axillary lymph node metastases with a tumor diameter < 5 cm, histological grade 1 or 2, and Ki67 ≥ 20% were included in cohort 2. Here, MKI67 is linked to metastatic malignant neoplasm in the lymph nodes.