Estrogen receptor (ER)-positive, HER2-negative postmenopausal advanced breast cancer

Estrogen receptor (ER)-positive, HER2-negative postmenopausal advanced breast cancer refers to a locally advanced or metastatic malignancy of the mammary epithelium occurring in individuals who have experienced the permanent cessation of ovarian function Pathophysiologically, the tumor cells express estrogen receptors that promote hormone-driven cellular proliferation, while lacking overexpression of human epidermal growth factor receptor 2 protein or *ERBB2* gene amplification The advanced stag...

Estrogen receptor (ER)-positive, HER2-negative postmenopausal advanced breast cancer refers to a locally advanced or metastatic malignancy of the mammary epithelium occurring in individuals who have experienced the permanent cessation of ovarian function The advanced stage denotes disease that has spread extensively within local tissues, regional lymphatics, or distant organs, rendering it generally incurable with curative-intent surgery

Pathophysiologically, the tumor cells express estrogen receptors that promote hormone-driven cellular proliferation, while lacking overexpression of human epidermal growth factor receptor 2 protein or *ERBB2* gene amplification This biological subtype represents the most common form of advanced breast cancer and is primarily managed with systemic endocrine-based regimens