ERBB2 and neoplasm: We retrospectively reviewed 647 patients with HR-positive, HER2-negative, node-positive EBC and classified them into the following four groups: group 1: ≥ 4 positive axillary lymph nodes (pALNs) or 1–3 pALNs and either grade 3 of both grading systems or tumors ≥ 5 cm; group 2: 1–3 pALNs, grade < 3, tumor < 5 cm, and Ki-67 ≥ 20%; group 3: 1–3 pALNs, grade < 3, tumor < 5 cm, and Ki-67 < 20%; and group 4: group 2 or 3 by HG classification but group 1 by NG classification.