Advanced breast cancer progress post-antiestrogen therapy

Advanced breast cancer that progresses post-antiestrogen therapy describes hormone receptor–positive, locally advanced or metastatic breast malignancy that exhibits objective disease progression or recurrence following treatment with endocrine-directed agents, such as selective estrogen receptor modulators or aromatase inhibitors

Advanced breast cancer that progresses post-antiestrogen therapy describes hormone receptor–positive, locally advanced or metastatic breast malignancy that exhibits objective disease progression or recurrence following treatment with endocrine-directed agents, such as selective estrogen receptor modulators or aromatase inhibitors

Advanced breast cancer that progresses post-antiestrogen therapy describes hormone receptor–positive, locally advanced or metastatic breast malignancy that exhibits objective disease progression or recurrence following treatment with endocrine-directed agents, such as selective estrogen receptor modulators or aromatase inhibitors

This clinical state represents endocrine-resistant disease, characterized pathophysiologically by the reactivation of oncogenic growth despite estrogen signaling blockade

This clinical state represents endocrine-resistant disease, characterized pathophysiologically by the reactivation of oncogenic growth despite estrogen signaling blockade Tumors frequently develop acquired molecular adaptations, including activating mutations in the estrogen receptor alpha gene (*ESR1*), loss of estrogen receptor expression, or compensatory upregulation of alternative signaling cascades such as the cyclin D–CDK4/6, PI3K/AKT/mTOR, and receptor tyrosine kinase pathways

Tumors frequently develop acquired molecular adaptations, including activating mutations in the estrogen receptor alpha gene (*ESR1*), loss of estrogen receptor expression, or compensatory upregulation of alternative signaling cascades such as the cyclin D–CDK4/6, PI3K/AKT/mTOR, and receptor tyrosine kinase pathways

Tumors frequently develop acquired molecular adaptations, including activating mutations in the estrogen receptor alpha gene (*ESR1*), loss of estrogen receptor expression, or compensatory upregulation of alternative signaling cascades such as the cyclin D–CDK4/6, PI3K/AKT/mTOR, and receptor tyrosine kinase pathways