Since the activation of PI3K/Akt/mTOR and MAPK/Erk signaling pathways correlates with worse clinical outcomes in breast cancer[47,48], our results suggest that HR+/HER2+ breast cancer patients receiving co-targeted therapies including trastuzumab and fulvestrant in combination could probably have a better prognosis than those receiving fulvestrant alone. Here, ERBB2 is linked to breast carcinoma.