A class of drugs called aromatase inhibitors, which are used to ward off the recurrence of breast cancer after surgery, increase the risk of cardiovascular disorders more than treatment with tamoxifen.

Previous reports have suggested a trend toward increased cardiac events in association with aromatase inhibitors.

An analysis of data from seven studies, involving a total of nearly 20,000 postmenopausal women with early breast cancer, showed a 31 percent relative increase in cardiovascular adverse compared with tamoxifen treatment.

However, the overall rate of all side effects, including blood clots and strokes, was higher among women given tamoxifen.