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A safety analysis of a large multicenter trial that compared letrozole and tamoxifen in postmenopausal women with early breast cancer shows cardiovascular events are rare with these drugs, Dr. Alan S. Coates reported.
The analysis also confirms that letrozole (Femara) is associated with more cardiac adverse events (2.4% vs. 1.4%, P = .004) , whereas tamoxifen is linked to more thromboembolic events (2.3% vs. 0.9%, P less than .001), said Dr. Coates, professor of medicine at the University of Sydney in Australia.
The phase III Breast International Group (BIG) 1-98 trial compared 5 years of adjuvant treatment with the two agents in hormone receptor-positive breast cancer. Sponsored by Novartis, maker of letrozole, it concluded the aromatase inhibitor was significantly better at reducing risk of recurrence, especially at distant sites (N. Engl. J. Med. 2005;353:2747-57).
Dr. Coates, cochair of the International Breast Cancer Study Group, said the safety analysis compared the incidence and timing of cardiovascular adverse events, baseline cardiac risk factors, prior cholesterol levels, and serial cholesterol measurements in 7,963 patients. He said he was reassured by the analysis and cautioned that the excess cardiac events seen with letrozole "may not be real because you can never be certain about an event that you see only in an unplanned subset analysis." Any difference is outweighed by better disease control with letrozole, he said.
Coates A.S. et al. Cardiovascular adverse events during adjuvant endocrine therapy for early breast cancer using letrozole or tamoxifen: Updated safety analysis of trial BIG 1-98. Abstract 521.
Commentary |
This unplanned subset analysis shows an increase in cardiovascular events that, although significant, is small: 57 vs. 96 events in almost 4,000 women. We do need to identify characteristics that could place women at higher risk for these events. The benefit of aromatase inhibition appears to outweigh the modest risks suggested by this analysis. — Hope S. Rugo, M.D.
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