Tamoxifen for Breast Cancer Prevention Has No Heart-Related Effects

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

"We found that cardiovascular event rates were notstatistically significantly different between women assigned to tamoxifen orplacebo, independent of preexisting coronary heart disease," said StevenReis, MD, principal investigator in the study, associate professor of medicineat the University of Pittsburgh School of Medicine, and director of the Women’sHeart Center at UPMC Health System’s Cardiovascular Institute. "Thesefindings should provide a degree of comfort to those women who are takingtamoxifen for breast cancer prevention."

Between 1992 and 1997, 13,388 women at increased risk for breastcancer 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 aprior history of clinical coronary heart disease. The remaining 12,146 women hadno such history.

No Difference in Cardiovascular Events

The study found that women who had coronary heart disease whenthey entered the study had a higher rate of cardiovascular events than did womenwithout heart problems. However, within each group, there was no difference inthe rate of cardiovascular events between those receiving tamoxifen and thosereceiving a placebo.

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

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

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

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