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Tamoxifen for Breast Cancer Prevention Has No Heart-Related Effects

Tamoxifen for Breast Cancer Prevention Has No Heart-Related Effects

Tamoxifen (Nolvadex) does not affect cardiovascular risk in healthy women or those with coronary heart disease, according to a study published in the Journal of the National Cancer Institute (93:16-21, 2001). The study is part of the National Surgical Adjuvant Breast and Bowel Project’s Breast Cancer Prevention Trial.

"We found that cardiovascular event rates were not statistically significantly different between women assigned to tamoxifen or placebo, independent of preexisting coronary heart disease," said Steven Reis, MD, principal investigator in the study, associate professor of medicine at the University of Pittsburgh School of Medicine, and director of the Women’s Heart Center at UPMC Health System’s Cardiovascular Institute. "These findings should provide a degree of comfort to those women who are taking tamoxifen for breast cancer prevention."

Between 1992 and 1997, 13,388 women at increased risk for breast cancer were randomly assigned to receive tamoxifen or a placebo. After 4 years, 13,194 women were available for cardiovascular follow-up, 1,048 of whom had a prior history of clinical coronary heart disease. The remaining 12,146 women had no such history.

No Difference in Cardiovascular Events

The study found that women who had coronary heart disease when they entered the study had a higher rate of cardiovascular events than did women without heart problems. However, within each group, there was no difference in the rate of cardiovascular events between those receiving tamoxifen and those receiving a placebo.

There were 72 cardiovascular events among the 6,604 tamoxifen users and 68 among the 6,590 women assigned to placebo. No differences were noted in the incidence of fatal heart attack, nonfatal heart attack, unstable angina, or severe angina.

Among the 12,146 women without a history of clinical coronary heart disease, there were 96 cardiovascular events—47 in the tamoxifen group and 49 in the placebo group. Cardiovascular events for the 1,048 women with a prior history of clinical coronary heart disease also failed to show any statistically significant differences between the treatment groups.

"Although the event rates in the group of women with a prior history of heart disease are greater than those observed in the group of women without a history of heart disease, these data demonstrate that assignment to tamoxifen did not affect cardiovascular events in this high-risk population," said Dr. Reis. In this group, there were 25 cardiovascular events in the tamoxifen group and 19 in the placebo group.

"Because tamoxifen is increasingly being prescribed for the prevention and treatment of breast cancer, longer-term clinical trials of tamoxifen in women are needed to further elucidate its long-term cardiovascular effects," said Dr. Reis.

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