Out of a total of 67 collected specimens, the following numbers of samples were subjected to a complete IHC assessment of paired breast PTs and ALN metastatic tumors: 47 samples for ER, 44 samples for PR, 49 samples for HER2, 43 samples for Ki-67, 23 samples for E-cadherin, 44 samples for cyclin D1, 42 samples for Bcl-2, 50 samples for GCDFP-15, 21 samples for Snail+Slug, 22 samples for PD-L1, and 21 samples for PRL-3 [other reports on the heterogeneity of GCDFP-15 and PRL-3 expression in BC have been previously published elsewhere (35, 36)]. This evidence concerns the gene ESR1 and metastatic neoplasm.