PGR and triple-negative breast carcinoma: Triple negative breast cancer (TNBC), which lacks expression of oestrogen receptor (ER), progesterone receptor (PR), or human epidermal growth factor receptor 2 (HER2), makes up 10–15% of all diagnosed breast cancers3 and remains a problem aggressive disease, with a reported five-year survival rate ranging from 62 to 77%4–9.