PGR and breast cancer: Indeed, breast cancer subtypes are classified, using a nonspecific hormone receptor status HR and the HER2 receptor status, as luminal A (HR+/HER2-), luminal B (HR+/HER2+), HER2 enriched (HR-/HER2+), and Triple negative (HR-/HER2-), where HR-stands for both ER- and PR-, while HR+ stands for either ER+ or PR+, as if ER and PR status could mutually back up each other.