Tamoxifen Complications

If you're at increased risk for breast cancer, your doctor may have recommended taking Tamoxifen to reduce your risk. However, a study of the side effects of Tamoxifen can make the cure seem as scary as the problem. You'll have to weigh many factors to decide whether the benefit from Tamoxifen outweighs the risk.

Identification

• Tamoxifen is a drug used to fight breast cancer by blocking estrogen. In addition to being used by women with breast cancer, the Breast Cancer Prevention Trial, a study done during the 1990s, showed that Tamoxifen is useful for preventing breast cancer in women who are at increased risk for the disease. It's also used for women who are in remission from breast cancer to reduce the risk of a future recurrence.

Eligibility

• Because of the possibility of serious side effects from Tamoxifen, only certain women are eligible to take the drug. Loosely defined, women who are at increased risk for breast cancer are eligible. Specifically, there are several qualifications that define an increased risk. Women over age 60 automatically qualify. In women between ages 35 and 59, risk factors include having had breast cancer in the past, having at least three close relatives who have had breast cancer, having the breast cancer gene, starting menstrual periods before age 12, having no children or having your first child after age 30 and reaching menopause after age 55.

Side Effects

• The possible side effects of Tamoxifen may be scary enough to keep women from taking the drug. One of the most frightening findings of the Breast Cancer Prevention Trial was that women taking Tamoxifen had two and a half times the risk of developing endometrial cancer compared to women who took a placebo. It should be noted, though, that even this rate was two women out of a thousand.

  Women taking Tamoxifen are at increased risk of blood clots, leading to a possible pulmonary embolism or deep-vein thrombosis. You may also experience uterine abnormalities, such as a thickening of the uterine wall or developing fibroids. Tamoxifen may also increase your risk of cataracts or other eye problems. There is also an increased risk of strokes among women on Tamoxifen, possibly related to the blood-clotting issues.

Reducing Effects

• If you're taking Tamoxifen, it's vital that you get regular gynecological exams. Your doctor should be on the lookout for endometriosis, keeping in mind that possible fibroids or uterine thickening may make it more difficult to spot. It's recommended that if you're about to start taking Tamoxifen, you should have an endometrial sampling done beforehand to make sure there are no pre-existing problems.

  The recommended length of time for taking Tamoxifen is five years. Researchers have found no additional benefit to taking it longer, but the risk of side effects increased with longer usage.

Considerations

• You and your doctor will have to weigh your risk factors for breast cancer against your risk factors for side effects before deciding whether or not you should take Tamoxifen. In general, younger eligible women are more likely to benefit from the drug than older women.

  Women who have had blood clots or are on blood-thinning medications should not take Tamoxifen. Women with risk factors for blood clots, such as high blood pressure, obesity, diabetes or a history of smoking, should stay away from Tamoxifen as well.

  Pregnant or nursing mothers may not take Tamoxifen.