Tamoxifen, an antiestrogen agent that has been used for >20 years to treat breast cancer, does not increase a woman's risk for stroke. Earlier studies had indicated that the drug could increase a woman's risk. Reporting in the Journal of the National Cancer Institute (October 20, 2004), study coauthor Ann Geiger, PhD, said that the previous studies did not independently confirm the stroke diagnosis, and they did not control the data for the participants'other risk factors for stroke.
Therefore, the researchers enrolled >11,000 women who had been diagnosed with breast cancer between 1980 and 2000 and evaluated the risk of stroke from tamoxifen treatment. The data showed that 422 women had possible strokes. Of these 422 women, 49 were excluded because the stroke happened prior to the breast cancer diagnosis. Another 194 were not eligible either because their stroke could not be confirmed or because the researchers could not gather enough tamoxifen information.
The remaining 179 women with confirmed strokes after their breast cancer diagnosis were compared with 431 control patients who were age-matched and had similar breast cancers. The researchers found no connection between tamoxifen and stroke.