Breast Disease pp 419-447 | Cite as

Treatment of Metastatic Breast Cancer: Endocrine Therapy

  • Fatma Sen
  • Adnan Aydiner


Estrogen plays a primary role in breast cancer carcinogenesis and functions similarly to growth factors in some subtypes of breast cancer cells, particularly hormone receptor-positive (HR+) cells. Reducing estrogen production and preventing estrogen from interacting with the estrogen receptor pathway have been the focus of several preclinical and clinical trials and are commonly used strategies for treating HR+ breast cancer. Because the ovaries are the main source of estrogen in premenopausal women, ovarian ablation or functional suppression is the primary means of decreasing circulating estrogen. In postmenopausal women, estrogen production by the ovaries is functionally inactive, and the peripheral conversion of androgens to estrogen is the predominant source of estrogen. Thus, the inhibition of the conversion of androgens by an aromatase inhibitor and of the interaction of estrogen with its receptor are the most frequently used approaches to treat postmenopausal women with HR+ breast cancer. Initial endocrine treatment is a relevant option for patients with locally advanced or metastatic HR+ breast cancer who have no or mild symptomatic disease. Patients in whom breast cancer has progressed during the adjuvant or first-line endocrine treatment or within 1 year after adjuvant endocrine treatment termination should be evaluated for a non-cross-resistant second-line endocrine agent. The concurrent administration of an endocrine agent with a human epidermal growth factor receptor (HER2)-directed agent is also widely accepted for breast cancer patients with both HR and HER2 receptor positivity.


Metastatic disease Breast cancer Premenopausal Postmenopausal Endocrine treatment Hormone receptor-positive CDK4/6 inhibitor M-TOR inhibitor Aromatase inhibitor Fulvestrant Ribociclib Palbociclib Abemaciclib Everolimus 


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Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  • Fatma Sen
    • 1
  • Adnan Aydiner
    • 2
  1. 1.Department of Medical OncologyAvrasya HospitalIstanbulTurkey
  2. 2.Oncology Institute, Istanbul Medical FacultyIstanbul UniversityIstanbulTurkey

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