Tamoxifen (Nolvadex) has been used for over 30 years to treat breast cancers that are hormone-receptor positive. Figure 5.6 below shows how tamoxifen works. It attaches to the hormone receptor on the surface of the cancer cell, blocking the hormone estrogen from attaching to the cell. Since hormone-receptor positive cells need estrogen to grow, tamoxifen can slow or stop the growth of cancer cells. Unlike aromatase inhibitors, tamoxifen can be used to treat breast cancer in both premenopausal and postmenopausal women.
Source: British Broadcasting Corporation
Tamoxifen is a pill that is taken every day, for up to five years. The benefits from tamoxifen last long after women stop taking it. Clinical trials continue to explore the use of tamoxifen beyond five years. Results to date suggest there is no added benefit for taking tamoxifen for more than five years, but there is a continued increased risk of side effects.
Certain types of anti-depressants called selective serotonin reuptake inhibitors (SSRIs) can interfere with the metabolism of tamoxifen (how tamoxifen works in the body). Some SSRIs (such as Prozac, Paxil and Zoloft) interfere with tamoxifen metabolism to such a degree that they should not be taken while on tamoxifen [23]. If you are taking SSRIs to treat depression or menopausal symptoms talk to your health care provider about possible drug interactions and other options for treating symptoms.
Tamoxifen as chemoprevention (a risk-lowering drug)
Among cancer-free women who have a high risk of breast cancer, including those with atypical hyperplasia and lobular carcinoma in situ, tamoxifen can be taken to lower risk. For more information on risk-lowering drugs and other options for women at high risk of breast cancer, see the Risk Factors section.
Updated 08/25/09
