Tamoxifen is a drug which interferes with and blocks the activity of estrogen. Estrogen is a female hormone that can promote the growth of breast cancer in both women and men. Therefore, tamoxifen has been widely used to treat and to prevent breast cancer. In addition to its therapeutic effects against breast cancer, tamoxifen has been shown to be an effective treatment for a host of other conditions, including bipolar disorder and infertility.
Breast Cancer Treatment
Tamoxifen is widely used to treat early stage breast cancers and metastatic breast cancers in both women and men. As tamoxifen blocks estrogen receptors, only patients with estrogen-receptor (ER) positive breast cancers will respond to tamoxifen therapy. According to breastcancer.org, tamoxifen therapy reduces risk of breast cancer recurrence by 30 to 50 percent. In some cases, tamoxifen is used to reduce tumor size prior to surgery of ER-positive tumors.
Breast Cancer Prevention
Tamoxifen is also used to reduce the risk of developing breast cancer in patients who are at high risk for the disease. These include patients who've had a negative breast biopsy or who have family members (e.g., mother, sister or daughter) with a history of breast cancer. The American Cancer Society recommends that women with a five-year risk of breast cancer greater than 1.66 percent should consult their physicians about tamoxifen therapy.
According to a 2002 study published in "Lancet," tamoxifen therapy reduces the risk of ER-positive breast cancer by 48 percent, and has no statistically significant effect on risk of ER-negative breast cancer.
Other Positive Effects
Tamoxifen has been shown to reduce rate of bone loss in post-menopausal women. According to a 1998 study published in the "Journal of National Cancer Institute," tamoxifen therapy reduces the risk of osteoporotic fractures (including hip, spine, wrist and forearm fractures) by 20 percent.
Tamoxifen also has been shown to ameliorates mania in bipolar disorder patients, according to medscape.com.
Since tamoxifen increases ovulation, it has been used at high doses to stimulate egg production in women with fertility issues, according to breastcancer.org.
References
- BreastCancer.Org: Tamoxifen
- "Journal of the National Cancer Institute"; Tamoxifen for prevention of breast cancer: report of the National Surgical Adjuvant Breast Cancer and Bowel Project; Fisher, et al.; September 1998
- "Lancet"; First results from the International Breast Cancer Intervention Study (IBIS-I): a randomised prevention trial; Cuzick, et al.; September 2002
