In this diagnostic/prognostic study, the predictive models and corresponding nomograms for high nodal burden (≥pN2) in patients with 1 or 2 SLN macrometastases and luminal ERBB2-negative breast cancer and ILC, respectively, may help select patients for intensified adjuvant therapies while avoiding CALND. The gene discussed is ERBB2; the disease is breast carcinoma.