Estrogens and antiestrogens

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Estrogens and antiestrogens


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Estrogens and antiestrogens

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A 57-year-old woman presents to the medical oncology clinic to discuss next steps for her metastatic breast cancer. The patient initially noticed a lump in her left axillary breast one year ago. After an initial lumpectomy, a diagnostic lymph node dissection showed metastasis to 4 of 6 lymph nodes. The tumor was found to be hormone receptor-positive and HER2 negative. A subsequent PET scan of the thorax demonstrated metastases in the left lung. During this visit, palliative care options are discussed with the patient. Which of the following drugs should be prescribed to reduce tumor burden by targeting the hormone receptors of this tumor?  

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Breast cancer

tamoxifen for p. 450

Deep venous thrombosis (DVT) p. 697

tamoxifen/raloxifen and p. 449

Endometrial cancer

tamoxifen and p. 450

Pulmonary embolism p. 697

tamoxifen/raloxifene and p. 449

Tamoxifen p. 450, 680

for breast cancer p. 727

hot flashes with p. 250


Synthetic estrogens are a class of medications that act like natural estrogens and are mainly used for primary hypogonadism, primary amenorrhea, estrogen deficiency, and as contraceptives.

Now, antiestrogens, or estrogen antagonists include full antagonists, which antagonize natural estrogens in all tissues, and selective estrogen receptor modulators, or SERMs, which act as estrogen antagonists in some tissues but also act as estrogen agonists in others.

Full antagonists and SERMs are used for breast cancer, and SERMs are also used for osteoporosis.

But first let’s talk a bit about natural estrogen, which plays a big role in the menstrual cycle.

The hypothalamus, which is part of the brain, secretes gonadotropin-releasing hormone, or GnRH, which travels to the nearby pituitary gland and stimulates it to secrete two hormones follicle stimulating hormone, or FSH, and luteinizing hormone, or LH.

FSH and LH make the ovarian follicles, which are scattered throughout the ovaries, develop and secrete the female sex hormones, estrogens and progesterone.

These hormones gradually increase during the first 2 weeks of the cycle, called the follicular phase, but estrogen is the main hormone synthesized during this phase.


  1. "Katzung & Trevor's Pharmacology Examination and Board Review,12th Edition" McGraw-Hill Education / Medical (2018)
  2. "Rang and Dale's Pharmacology" Elsevier (2019)
  3. "Goodman and Gilman's The Pharmacological Basis of Therapeutics, 13th Edition" McGraw-Hill Education / Medical (2017)
  4. "International Union of Pharmacology. LXIV. Estrogen Receptors" Pharmacological Reviews (2006)
  5. "The Role of Estrogens in Control of Energy Balance and Glucose Homeostasis" Endocrine Reviews (2013)
  6. "Selective estrogen receptor modulators (SERMs) and selective estrogen receptor degraders (SERDs) in cancer treatment" Pharmacology & Therapeutics (2018)

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