PGR and breast cancer: Four main subtypes of BC have been established based on immunohistochemistry (IHC) biomarkers: Luminal A (estrogen and/or progesterone-receptor positive, HER-2 negative and have the best prognosis), Luminal B (estrogen and/or progesterone-receptor positive and either HER-2 positive or HER-2 negative), HER-2 overexpressed and Triple negative (which are negative for the three main biomarkers and have the worst prognosis) [11].