Slightly increased risk of ischemic stroke found with tamoxifen.

2004 NOV 4 - (NewsRx.com & NewsRx.net) -- Researchers at Duke University Medical Center have found a slightly elevated risk of ischemic stroke due to a blood clot in the brain in patients treated with tamoxifen, a drug commonly prescribed both for preventing breast cancer and treating women with the disease.

The researchers emphasize that this slight increase in risk does not mean that use of tamoxifen should be reduced, given the drug's considerable benefits. Rather, they say, it means that women should be screened for possible stroke risk before the drug is prescribed for them.

Tamoxifen is known to increase the risk of thromboembolism - blockage of a blood vessel by a blood clot - but its relationship to stroke risk has been unclear. Because of the risk of thromboembolism, tamoxifen could theoretically be associated with higher risk of arterial obstruction in the brain and could cause ischemic stroke - versus a hemorrhagic stroke in which a vessel bursts and bleeds into the brain, the researchers said.

However, they said, no studies have yet been designed specifically to evaluate the stroke risk in patients taking tamoxifen.

The Duke team performed a meta-analysis of tamoxifen research conducted since 1980 in which patients were randomized to either tamoxifen versus placebo or tamoxifen versus other therapies. Their objective was to assess both the overall risk of ischemic strokes and all strokes in those who have taken the drug. Their findings appeared in the October 12, 2004, issue of Neurology.

"The absolute increase in risk of strokes in patients taking this drug is very small but important," said Cheryl Bushnell, MD, a neurologist at Duke and lead author on the study. "Our findings support the practice of careful screening of women, particularly those who are older, being considered for tamoxifen therapy. In many women, the risk of stroke with tamoxifen may outweigh the benefit of treating or preventing breast cancer. Women should not stop their prescribed therapy based on these findings."

Bushnell and her Duke colleague, Larry Goldstein, MD, a neurologist and senior author on the paper, conducted a systematic review of all clinical trials of tamoxifen published since 1980 using the biomedical database MEDLINE, maintained by the National Library of Medicine. Nine trials met their inclusion criteria. Of the 39,601 total subjects enrolled, 19,954 were randomly designated to receive tamoxifen. The average age of women enrolled in the studies ranged from 47 to 65. Six trials specifically reported ischemic stroke events. All trials used a standard dose (20 milligrams per day) of tamoxifen.