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FDA Approves Tamoxifen For Women With Ductal Carcinoma in Situ (dateline July 6, 2000)


Tamoxifen, the most commonly prescribed drug used to help treat breast cancer and prevent the disease in high risk women, has recently been approved by the U.S. Food and Drug Administration (FDA) for a new use: to help prevent invasive breast cancer in women with ductal carcinoma in situ (DCIS).  DCIS is the most common type of non-invasive breast cancer.  According to estimates by the American Cancer Society, approximately 41,000 women will be diagnosed with DCIS in 2000.  Between 20% and 30% of all breast cancers detected on mammograms are DCIS. 

According to a spokeswoman for AstraZencea, the drug company that manufactures tamoxifen, nearly 20% of all newly diagnosed breast cancers are DCIS.  DCIS is a Stage 0 breast cancer (the earliest stage) that is confined to the milk ducts of the breast.  DCIS is typically treated with breast-conserving surgery ( lumpectomy)  and radiation or with mastectomy (breast removal). 

As with any type of cancer, women with DCIS are at risk of breast cancer recurrence (return), particularly if they are treated with breast-conserving therapy. The risk of recurrence is much higher (around 50%) among women who do not receive radiation after lumpectomy.  Women who are treated with mastectomy may be less likely to experience a recurrence of cancer because more breast tissue is removed; however, it is still possible for breast cancer to return.  

The FDA has now approved the use of tamoxifen in women with DCIS to reduce the risk of invasive breast cancer later in life.  Unlike DCIS, which is a non-invasive form of breast cancer, invasive breast cancer is able to break through the breast ducts or lobular walls and invade surrounding fatty and connective tissues of the breast.  From these areas, breast cancer can spread ( metastasize) to the axillary (underarm) lymph nodes and eventually, to other regions of the body. 

In addition to preventing breast cancer recurrence in DCIS patients, tamoxifen is also FDA approved to help treat early and advanced stages of breast cancer.  Additionally, tamoxifen is FDA approved to help prevent breast cancer in women at high-risk of the disease, such as those with lobular carcinoma in situ (a marker for breast cancer risk) and/or a strong family history of the disease. 

As with all drugs, the side effects of tamoxifen will vary from patient to patient.  Side effects of tamoxifen may include:

  • Hot flashes
  • Irregular menstrual cycles
  • Unusual vaginal discharge or bleeding
  • Irritation of the skin around the vagina
  • Nausea
  • Weight gain or loss
  • Mood changes

  • Cataracts or other eye problems

Tamoxifen can also increase the chances for endometrial cancer (cancer of the lining of the uterine), deep vein thrombosis (blood clots in large veins, particularly in the legs) pulmonary embolism (blood clot in the lung), and possibly stroke.   

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