PGR and triple-negative breast carcinoma: High tumour cell PDGFRα expression has been linked to lymph node metastasis, human epidermal growth factor receptor 2 (HER2) positivity [7], high histologic grade, oestrogen receptor (ER) negativity, progesterone receptor (PR) negativity and the triple-negative breast cancer subtype (TNBC) [8, 9].