Tamoxifen use for the treatment of breast cancer is not associated with an increased risk of stroke

Tamoxifen use for the treatment of breast cancer is not associated with an increased risk of stroke, according to a new study in the October 20 issue of the Journal of the National Cancer Institute. However, chemotherapy use is associated with an increased risk of stroke, regardless of tamoxifen use.

Tamoxifen has been used for the treatment of postmenopausal breast cancer since 1978. Since then, the drug has also been shown to reduce the risk of contralateral breast cancer and breast cancer recurrence and to halve the risk of breast cancer in women at high risk for the disease. However, tamoxifen use does have the potential for serious side effects. One of those side effects, an increased risk of stroke, was suggested in two large randomized trials but not in other studies.

To assess the impact of tamoxifen treatment for breast cancer on stroke risk, Ann M. Geiger, Ph.D., of Kaiser Permanente Southern California in Pasadena, and colleagues conducted a nested case–control study among women from Los Angeles County who were enrolled in a large health maintenance organization and were diagnosed with breast cancer between 1980 and 2000.

Use of tamoxifen was not associated with risk of stroke, either overall or when grouped by duration of use, dose of the drug, or how recently the drug was used. However, use of chemotherapy--but not a specific chemotherapy regimen--was associated with an increased risk of stroke, whether or not tamoxifen was used. Stroke was more common among women who had not yet completed menopause and in those who had a history of hypertension or diabetes requiring medication.

"Our study suggests that women and their clinicians considering tamoxifen use for breast cancer treatment can do so without concern for stroke," the authors write. With regard to the risk of stroke associated with use of chemotherapy, the authors add, "it seems logical that women with a history of chemotherapy may benefit from approaches to reduce stroke risk, such as appropriate management of hypertension and diabetes."