In terms of clinical risk factors, HER2-low disease was associated with positive HR status (89.4% vs. 79.8%, p < 0.001), well or moderately differentiated grade (well-differentiated: 26.5% vs. 23.8%; moderately differentiated: 46.1% vs. 42.1%, p < 0.001), ductal adenocarcinoma (76.1% vs. 72.4%, p < 0.001), and clinical stage I (64.5% vs. 63.2%, p < 0.001) but more lymph node involvement at diagnosis (no lymph node 69.7% vs. 71.0%, p < 0.001). This evidence concerns the gene ERBB2 and invasive ductal breast carcinoma.