Breast cancer

Hormonal therapy

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Last staff update: 10 May 2021

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PubMed Search: Hormonal therapy [title] breast [title]

Emily S. Reisenbichler, M.D.
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Cite this page: Reisenbichler ES. Hormonal therapy. website. Accessed September 30th, 2023.
Definition / general
  • Endocrine / hormonal therapy may be utilized in the treatment of hormone receptor positive breast carcinoma in the adjuvant (postoperative) or neoadjuvant (preoperative) setting
  • Most commonly used endocrine therapies are the antiestrogen / inhibiting agent tamoxifen or aromatase inhibitors (e.g. letrozole, anastrozole)
Essential features
  • Hormone receptor positive breast carcinomas may be treated with neoadjuvant endocrine therapy with lower toxicity and cost than the alternative of neoadjuvant chemotherapy
  • Neoadjuvant endocrine therapy with aromatase inhibitors shows response rates similar to those seen with neoadjuvant chemotherapy (JAMA Oncol 2016;2:1477)
  • Change in proliferative rate (as measured by Ki67), in the pre- vs posttreatment tumor, is related to long term prognosis and is a validated endpoint for neoadjuvant endocrine therapy (Eur J Surg Oncol 2016;42:333, Oncotarget 2017;8:26122)
Prognostic factors
Microscopic (histologic) description
  • Microscopic effects in invasive breast carcinomas (Eur J Cancer 2003;39:462)
    • Treatment with the aromatase inhibitor, letrozole, results in decreased mitoses and decreased progesterone receptor expression
    • Treatment with the antiestrogen / inhibiting agent, tamoxifen, results in increased tubule formation, decreased estrogen receptor expression and increased progesterone receptor
  • Microscopic effects in ductal carcinoma in situ (DCIS) (BMC Cancer 2009;9:285)
    • Treatment with antiestrogen therapy results in increased multinucleated histiocytes and degenerated cells, decrease duct extension and prominent periductal fibrosis
Microscopic (histologic) images

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Various images

Molecular / cytogenetics description
  • Invasive lobular and invasive ductal carcinomas demonstrate similar molecular changes in gene expression in response to endocrine therapy, such as downregulation of proliferation genes and upregulation of immune function and extracellular matrix remodeling genes (Cancer Res 2014;74:5371)
Board review style question #1
What tumor change, in response to preoperative endocrine therapy, would be considered predictive of a favorable outcome?

  1. Decreased histiocytes
  2. Decreased tubule formation
  3. Increased estrogen receptor expression
  4. Increased tumor cellularity
  5. Lower proliferative index
Board review style answer #1
E. The effects of preoperative endocrine therapy seen microscopically in the posttreatment surgical specimen may vary but most commonly include reduced tumor cellularity with decreased estrogen receptor expression in tumor cells. Response to therapy also typically includes increased histiocytic infiltration and tubule formation. A reduction in tumor proliferative index following endocrine therapy is associated with improved recurrence free survival.

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