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Breast Cancer and Hormone Therapy

Breast Cancer and Tamoxifen continued...

In addition, tamoxifen may offer an alternative to watchful waiting or prophylactic (preventative) mastectomy for women at high risk for developing breast cancer.

Tamoxifen is a type of drug called a selective estrogen-receptor modulator (SERM). In the breast, it functions as an anti-estrogen. Estrogen promotes the growth of breast cancer cells. Tamoxifen blocks estrogen from attaching to estrogen receptors on these cells. By doing this, it is believed that the growth of the breast cancer cells will be halted.

Tamoxifen is considered an option in the following cases:

  1. Treatment of ductal carcinoma in situ (DCIS) along with breast-sparing surgery or mastectomy.
  2. Adjuvant treatment of lobular carcinoma in situ (LCIS) to reduce the risk of developing more advanced breast cancer.
  3. Adjuvant treatment of breast cancer in men and women whose cancers are estrogen-receptor positive.
  4. Treatment of recurrent and metastatic breast cancer.
  5. To prevent breast cancer in women at high risk for developing the disease.

People who should not use tamoxifen include:

Talk to your doctor to see if tamoxifen is right for you.

For women, the side effects of tamoxifen are similar to some of the symptoms of menopause. Two of the most common side effects are hot flashes and vaginal discharge. Other tamoxifen side effects in women may include:

While some of its side effects are similar to menopausal symptoms, tamoxifen does not cause a woman to begin menopause.

Tamoxifen's side effects in men may include:

Are There Risks to Taking Tamoxifen?

Yes. The risks of taking tamoxifen include:

  • Fertility. Tamoxifen may affect fertility, so it is important to use some form of barrier birth control while you are taking it. However, do not use oral contraceptives (the "pill") since they may change the effects of tamoxifen and effect the breast cancer. Tell your doctor right away if you think you may have become pregnant while taking this medication.
  • Increased blood clots. Women taking tamoxifen may have a slightly increased risk of developing blood clots in the lungs or large veins. This risk is increased in smokers.
  • Increased risk of stroke.
  • Uterine cancer/sarcoma. Tamoxifen may increase a woman's risk of developing uterine cancer (cancer of the lining of the uterus) or uterine sarcoma. However, this risk is very small and needs to be balanced against the significant benefits of taking tamoxifen for breast cancer.
  • Cataracts. Taking tamoxifen appears to put some women at increased risk for developing cataracts, a clouding of the lens inside the eye. People have also reported eye problems such as corneal scarring or retinal changes.
  • Medications. Tamoxifen may affect the metabolism of other drugs.


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