Figure 1

Tumor classification (original magnification × 200). a) Luminal A: ER strongly positive, PR positive or negative, HER2 negative, CK5/6 and EGFR negative. b) Luminal B: ER weakly to moderately positive and/or PR positive, HER2 negative, CK5/6 and EGFR negative. c) HER2: HER2 positive, ER and PR negative, CK5/6 and EGFR negative. d) Basal: CK5/6 and/or EGFR positive, ER and PR negative, HER2 negative. e) Unclassified (penta-ve): ER and PR negative, HER2 negative, CK5/6 and EGFR negative. f) Hybrid: co-positivity of different markers in varied combination, an example of HER2-Basal hybrid (HBH) is shown.