PGR and breast cancer: Among the different types of BC, due to the lack of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2), triple-negative breast cancer (TNBC) has the highest mortality rate, a higher recurrence rate, more frequent metastasis, and a lack of sensitivity to current hormone therapies and other treatment methods; therefore, the search for novel treatment targets is necessary to develop new therapeutic strategies for TNBC [3].