Many women who take the drug tamoxifen to help prevent breast cancer report an onset of depression during treatment. However, after examining more than 11,000 women who participated in a U.S. national breast cancer prevention clinical trial, researchers did not find that women who took tamoxifen were any more likely to become depressed than women who were given a placebo, or inactive pill. According to the researchers, this finding should discourage physicians from ruling out certain women as candidates for tamoxifen based on their history or risk of depression.
Because of recent concerns that tamoxifen might be linked to depression, lead researcher Richard Day, PhD, of the University of Pittsburgh, and his colleagues examined the psychological effects of tamoxifen treatment in 11,064 women who participated in the National Surgical Adjuvant Breast and Bowel Project’s (NSABP) Breast Cancer Prevention Trial from 1992 to 1998. Every six months, the women were asked to complete a questionnaire that assessed their symptoms of depression. A "grading" scale was used to gauge the severity of depression among the women.
The results of the study found that women who were at higher risk of depression at the beginning of the study were more likely to exhibit symptoms of depression during the study. However, there was no correlation between the specific use of tamoxifen and depression. Women at high risk of depression who were given a placebo during the clinical trial were just as likely to become depressed as high-risk women who took tamoxifen.
Therefore, Dr. Day and his colleagues conclude that "physicians need not be overly concerned that treatment with tamoxifen will increase the risk for or exacerbate existing depression in women." However, the researchers also caution physicians not to dismiss women’s complaints of depression. Physicians should continue to screen for and treat potential cases of depression as they occur.
Tamoxifen is an "anti-estrogen" drug that has been used for over 20 years to help treat breast cancer. Tamoxifen works by competing with estrogen to bind to estrogen receptors in breast cancer cells. Since many breast cancer cells depend on estrogen for survival, blocking estrogen in effect starves these cancer cells. Tamoxifen has also been found to reduce the risk of breast cancer by 49% among women who are at high risk for the disease.
Researchers believed that tamoxifen might increase the risk of depression because it suppresses estrogen. Estrogen has been shown to improve mood and decrease the risk of depression among menopausal women. Thus an "anti-estrogen" drug such as tamoxifen may yield opposite results. However, the new study results reveal that this is not likely to be true.
Nevertheless, a small number of women who take tamoxifen experience sharp mood swings or become severely depressed. It may be difficult to determine whether tamoxifen is the source of these women's depression or if other stress factors (such as coping with breast cancer and/or going through natural menopause) contributed to the depression. Depending on the individual situation, depression may be treated with counseling or other medications. Some physicians recommend taking 30 to 60-day "breaks" from tamoxifen to help relieve depression.
Whether or not they are taking tamoxifen, women who experience depression should discuss any health problems with their physicians. Despite the concern of a link between tamoxifen and depression, the majority of women who take tamoxifen do not report symptoms of depression.
The most common side effects of tamoxifen include:
- Hot flashes
- Irregular menstrual cycles
- Unusual vaginal discharge or bleeding
- Irritation of the skin around the vagina
Tamoxifen is not appropriate for all women at high risk of breast cancer. Women who have a strong family history or other factors that increase their breast cancer risk should talk to their physicians about the most appropriate actions to help prevent or detect breast cancer in its earliest stages when it is most easily treatable.
- The study, "Tamoxifen and Depression: More Evidence From the National Surgical Adjuvant Breast and Bowel Project’s Breast Cancer Prevention (P-1) Randomized Study," is published in the November 7, 2001 issue of the Journal of the National Cancer Institute. An abstract of the study is available at http://www.jnci.oupjournals.org/
- The November 23, 2001 Reuters Health report, "Breast Cancer Drug Not Linked to Depression: Study," is available within 30 days of publication at http://www.reutershealth.com/
- To learn more about tamoxifen, please visit http://www.imaginis.com/breasthealth/tamoxifen.asp
- To learn more about coping with the side effects of tamoxifen, please visit http://www.imaginis.com/breasthealth/side_effects.asp
