PGR and breast cancer: A comprehensive study was performed in 2021 using the pan-pathogen microarray strategy to determine the breast cancer microbiome of the following four different subtypes: (1) ER and/or PR-positive, and HER2-negative (ER); (2) triple-positive that are ER, PR, and HER2-positive (TP); (3) HER2-positive and ER and PR-Negative (HR) (4) ER, PR, and HER2-negative (TN).