PGR and breast cancer: In addition to the traditional Tumor-Node-Metastasis (TNM) staging system, the treatment strategy of breast cancer is more dependent on its molecular typing characteristics, such as estrogen receptor (ER), progesterone receptor (PR), HER2, Ki67, and other risk factors like genomic markers (eg, BRCA1, BRCA2, and PIK3CA), and immunomarkers (eg, PD-L1) (2, 3).