The value of progesterone receptor expression in predicting pCR following NAC

Introduction: The efficacy of neoadjuvant chemotherapy (NAC), as measured by the pathological complete response (pCR), varies between molecular subtypes in breast cancer (BC). Oestrogen receptor positive (ER+), human epidermal growth factor 2 receptor negative (HER2-) patients tend to have lower pCR rates. This study aimed to determine if progesterone receptor (PR) expression, no longer routinely tested in ER+ BC, can identify which ER+/HER2- patients will achieve pCR.