ERBB2 and breast cancer: In total, 67 (71.3%) of BC/LNM pairs were concordant for surrogate subtyping, i.e., 37 patients in the Luminal A group, 19 patients in the Luminal B/HER2-negative group, 4 patients in the Luminal B/HER2-positive group, 1 patient in the Non-luminal/HER2-positive group, and 6 patients in the TNBC group (Table 4).