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 - Northwestern Memorial Hospital - Chicago

Drug Therapy

The following is a list of drugs used in the treatment of breast cancer:

Tamoxifen (Nolvadex)

Tamoxifen is a SERM (selective estrogen receptor modulator) that has been clinically proven to help reduce breast cancer risk by 45 to 50 percent. Tamoxifen is most commonly used to treat breast cancer in women or men. This drug may reduce the chance of breast cancer coming back in women previously treated with surgery, radiation or chemotherapy. It may also help prevent breast cancer in certain women with a high risk of developing breast cancer, as found in a study done by the NSABP (National Surgical Adjuvant Breast and Bowel Project) P-1 trial.

How Tamoxifen Works

Tamoxifen works by binding to the estrogen receptor located near the surface of each breast cell. It blocks estrogen from "landing" on the receptor which, in turn, prevents a cascade of reactions that stimulate various tumor growth factors. Tamoxifen is taken once daily for five years, and the benefit of the drug has been shown to last 10 to 15 years from discontinuation. It is not recommended that the drug be taken for a period longer than 5 years due to the associated risks.

Risks & Side Effects for Tamoxifen

There are serious risks and side effects of tamoxifen that should be discussed with your physician. Risks include, but are not limited to:

    • Blood clots
    • Uterine cancer
    • Uterine fibroids
    • Endometriosis
    • Progression of cataracts

Side effects include, but are not limited to:

    • Hot flashes
    • Vaginal dryness/discharge
    • Leg cramps
    • Changes in menstrual cycle

Raloxifene (Evista)

Raloxifene is also a SERM that has recently been shown to be effective in breast cancer prevention. It was studied in the NSABP P-2 trial, known as the STAR trial (study of tamoxifen and raloxifene). The STAR trial is a clinical trial designed see how the drug raloxifene compares with the drug tamoxifen in reducing the incidence of breast cancer in postmenopausal women that are at increased risk of the disease. It was one of the largest breast cancer prevention studies ever, and took place at more than 500 centers across the United States, Canada and Puerto Rico. Initial results of STAR show that the drug raloxifene is as effective as tamoxifen in reducing the breast cancer risk of the women on the trial with fewer side effects than tamoxifen.

Aromatase Inhibitors

Drugs included in this class are anastrozole (Arimidex), letrozole (Femara) and exemestane (Aromasin). The aromatase inhibitors (AIs) have only been approved for the treatment of breast cancer in postmenopausal women. Prior to the advent of AIs, women took tamoxifen for a period of five years with no additional therapy. Today there has been much debate as to whether or not eligible women should simply begin treatment with an AI for five years, begin treatment with tamoxifen for the first two and a half years followed by an AI for the remaining two and a half years, or to take tamoxifen for the full five years followed by treatment with an AI. The decision regarding treatment options should be discussed with your medical oncologist. Women treated with an AI should have their bone density monitored and supplement their diet with calcium and vitamin D, as the AIs have been shown to increase the risk of osteoporosis. The good news in regards to an AI versus tamoxifen is that AIs have a lower incidence of blood clots and endometrial cancer as opposed to tamoxifen.

Last UpdateJune 22, 2011
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