To be able to differentiate pre-metastatic and metastatic changes from potential tumor-type specific differences in patients with IDC, we selected groups of patients with the same basic primary tumor characteristics: luminal, estrogen receptor (ER) positive, human epidermal growth factor receptor 2 (HER2) negative, with and without LN metastasis (Table S1). The gene discussed is ESR1; the disease is neoplasm.