Tamoxifen is a drug that counteracts the effects of estrogen; the drug is used to treat breast cancer and prevent its recurrence. Tamoxifen blocks estrogenic effects on breast tissue, and slows the growth of cancer cells in the breast that have estrogen receptors. Although it acts as an anti-estrogenic in breast tissue, tamoxifen has an estrogenic effect on other tissue. Tamoxifen may also be taken by women who have the breast cancer gene or a strong family history of breast cancer, according to the Mayo Clinic.
Menopausal Side Effects
Tamoxifen causes some menopausal type side effects; these are the most common side effects of the drug. A five year clinical trial (B-14) by the National Surgical Adjuvant Breast and Bowel Project, whose results were reported on Druginfonet.com, found that hot flashes were the most common side effect of the drug, reported in 64 percent of women. According to the same study, vaginal discharge was reported by 30 of women, irregular menses by 25 percent, fluid retention by 32 percent, and weight gain by 38 percent.
Blood Clot and Stroke Risks
There's a small increase in blood clots in women taking tamoxifen compared to those taking a placebo, according to the National Cancer Institute. Pulmonary embolism, blood clots in the lung and deep vein thrombosis (blood clots in the legs) can occur. A study reported by Duke University Medical Center researchers in the Oct. 12, 2004, issue of "Neurology" found a small increased risk of stroke for women taking tamoxifen. The Duke researchers cautioned that more studies must be done to confirm whether a stroke risk exists.
Other Side Effects
Bone pain, rash, vaginal itching, headaches and nausea and vomiting are less common side effects in women taking tamoxifen, according to the Mayo Clinic, which also states that women taking tamoxifen have a small increase of eye side effects such as cataract development or blurred vision.
Cancer Risks
Tamoxifen can increase the risk of developing two types of cancer of the uterus; endometrial cancer, a cancer of the cell lining the uterus, and uterine sarcoma, a cancer of the muscle wall. According to the National Cancer Institute, studies show the risk for endometrial cancer to be 2 out of 1,000 in women taking tamoxifen, as opposed to 1 of 1,000 women taking placebos.Tamoxifen in large doses can cause liver cancer in laboratory rats, and may cause an increase in liver enzymes, but has not been proven to cause liver cancer in women, according to studies reported on the Drug Infonet website.
