Tamoxifen (Efficacy)

Tamoxifen is a non-steroidal anti-estrogen hormone antineoplastic (receptor antagonist with partial agonist activity). It is widely used to treat early, advanced and metastatic breast cancer in both women and men. Those patients who are ER + benefit most from tamoxifen therapy, although it is also used in those who are ER-. It is also used to prevent the possible development of the disease in individuals who have a high risk of suffering from it. As an adjuvant, 5-year mortality decreases by 20% with few adverse reactions.


Hypersensitivity and pregnancy.


Family history and risk factors for thrombosis should be assessed before tamoxifen is prescribed.

Caution should be exercised in patients at risk of endometrial cancer and uterine sarcoma.

In patients with breast cancer, before prescribing tamoxifen should be taken into account if there is a risk of second primary tumors in the endometrium and breast.

For prophylaxis in sexual activity, take contraceptive measures (barrier methods or non-hormonal contraceptives) if you are being treated with tamoxifen.

Avoid potent inhibitors of CYP2D6 (paroxetine, fluoxetine, quinidine, cinacalcet or bupropion) during treatment with tamoxifen.

Not recommended in children.


Hot flushes, ischemic cerebrovascular accidents, venous thromboembolism, deep vein thrombosis, pulmonary embolism, vaginal bleeding, vaginal discharge, vulvar pruritus, endometrial changes (including hyperplasia and polyps), menstrual irregularities, gastrointestinal intolerance, alopecia, rash, headache, dizziness, tumor-related symptoms, fluid retention, muscle cramps in the lower extremities.


Plasma levels of tamoxifen are diminished by rifampicin.

The anticoagulant effect of tamoxifen is increased by concomitant treatment with coumarin-type anticoagulants.

There is a risk of thromboembolic effects if tamoxifen is taken together with other cytotoxic agents.

In combination with aromatase inhibitor (as adjuvant therapy) has not been shown to be more effective than compared to tamoxifen alone.


  • Nolvadex ®

Gene or region studied

  • CYP2D6
  • CYP2C9
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