On the other hand, luminal B presents ER and may express PR, in addition to possibly expressing HER2 receptors and has a higher proliferation index than luminal A. HER2-positive breast cancer is characterized by the absence of hormone receptors and the presence of only HER2 receptors, and TNBC does not express any of these receptors, being the most aggressive subtype. This evidence concerns the gene PGR and breast cancer.