Tamoxifen (Nolvadex) has been used for over 30 years to treat breast cancers that are hormone-receptor positive. Figure 5.9 below shows how tamoxifen works. It attaches to the hormone receptor in the cancer cell, blocking estrogen from attaching to the receptor. 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.
Tamoxifen is also be used to treat breast cancer in men. Learn more about male breast cancer.
Figure 5.9
Source: British Broadcasting Corporation
Tamoxifen as breast cancer treatment
Treatment with tamoxifen lowers the risk of [47,51]:
- Breast cancer recurrence
- Breast cancer in the opposite breast
- Death from breast cancer
Tamoxifen is a pill taken every day for up to five years. The benefits from tamoxifen last long after you 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 risk of side effects.
Some 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 to such a degree that they should not be taken while on tamoxifen [32,52]. 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 developing breast cancer (including those with atypical hyperplasia or lobular carcinoma in situ) tamoxifen can be taken to lower risk [51,53].
Learn more about risk-lowering drugs and other options for women at high risk of breast cancer.
Learn more about tamoxifen on the National Institutes of Health's Medline Plus website.
Side effects of tamoxifen
The side effects of tamoxifen differ from those of other hormone therapies. Learn more about the side effects of tamoxifen.
Importance of following your breast cancer treatment plan
The importance of adherence (compliance)
Breast cancer treatment is most effective when all parts of the treatment plan are followed. Adherence (also called compliance) is how closely people follow the treatment plan (for medications and other therapies) prescribed by their health care providers in terms of:
Completing hormone therapy
Hormone therapy used to treat breast cancer is typically prescribed for at least five years. The length of treatment coupled with side effects can make adherence to hormone therapy difficult. Although the menopausal symptoms related to hormone therapy can be hard to deal with, there are treatments that may ease these side effects. If you have side effects with hormone therapy, talk to your health care provider about ways to treat them.
To get the most benefit of hormone therapy, you need to take the full course of treatment. Women who complete the full treatment course have higher rates of survival [50-51].
If you have trouble remembering to take your hormone therapy, a daily pillbox or setting an alarm on your watch or phone may help [3]. However, you do not need to panic if you miss a day or two.
Learn more about adherence.
Updated 04/17/12
