ERBB2 and breast cancer: To further investigate HEMTIRGs expression across BC subtypes, we employed GSEA to assess differences in hypoxia, EMT, and hypoxia-EMT risk scores in four BC subtypes: hormone receptor-positive (Luminal A and Luminal B), HER2-positive, and triple-negative BC (TNBC), revealing that TNBC exhibited consistently higher scores for these features compared to the other subtypes (Figures 8E–G).