The American Cancer Society describes tamoxifen as a drug that interferes with estrogen activity. It's one of the many medications used to treat breast cancer. But unlike the drugs used in chemotherapy, tamoxifen does nothing to damage the abnormal cells associated with the disease. Instead, it keeps estrogen from interacting with the cells that make up breast tissue. This is beneficial in the treatment of cancer because estrogen actually stimulates the growth of breast cancer cells, namely those considered estrogen receptor-positive cells. By inhibiting estrogen, it can keep breast cancer from recurring or reduce the risk of its development in women considered high-risk. But tamoxifen has its own set of risks.
Cancer
The National Cancer Institute warns that tamoxifen may cause cancer as it tries to prevent it. Some women taking tamoxifen as a course of treatment for breast cancer are at an increased risk of developing endometrial cancer, which is cancer originating in the lining of the uterus. It also increases the risk of uterine sarcoma. This form of cancer affects the muscles as well as other tissue supporting the uterus.
Cataracts
Another potential danger of tamoxifen is an increased risk of cataracts. This condition is marked by a clouding over the lens of the eye. As cataracts develop, your eyesight begins to seem foggy, making it difficult to see--especially in the dark. It also can make it hard to read, see things in the distance and drive. A surgical procedure can correct this problem if it arises.
Strokes
Tamoxifen also increases your risk of stroke. This is largely due to the increased number of blood clots that can occur during the systematic use of the medication. If a blood clot were to form within one of the arteries transporting blood to the brain, it could reduce or cut off the blood supply to the brain, depriving it of oxygen and other nutrients. This causes cells within the brain to die, eliciting dizziness, loss of balance, speech difficulties, vision disruptions, loss of consciousness and numbness or paralysis to one side of the body.
Side Effects
Besides the increased risk of serious complications such as cancer, cataracts and stroke, tamoxifen can cause uncomfortable side effects. Most of these side effects are minor, ranging from headaches, nausea and fatigue to hot flashes, vaginal discharge and menstrual irregularities. It may also cause weight loss, stomach cramps, constipation and weakness. If you experience any side effect from its use, contact your health care provider.
