The clinical subtypes are based on the expression of the estrogen receptor (ER) and the progesterone receptor (PR) and the amplification of the HER2 (ERBB2) receptor and include hormone receptor (HR)-positive (HR+/HER2−, also ER+/PR+/HER2−), triple-positive (HR+/HER2+, also ER+/PR+/HER2+), HER2-positive (ER−/PR−/HER2+, also HER2+), and triple-negative breast cancer (TNBC) (HR−/HER2−, also ER−/PR−/HER2−) [2,3,4]. Here, PGR is linked to triple-negative breast carcinoma.