Breast cancer drugs increase heart risk slightly

Aromatase inhibitors, a class of drugs used to ward off the recurrence of breast cancer after surgery, increase the risk of cardiovascular disorders slightly more than does treatment with tamoxifen, a new study shows.

Aromatase inhibitors are superior to tamoxifen in some circumstances, the researchers point out in the medical journal Cancer, but previous reports have suggested a trend toward increased cardiac events in association with their use.

To look into this, Dr. Federica Cuppone from Regina Elena National Cancer Institute, Rome, and colleagues analyzed data from seven studies involving a total of nearly 20,000 postmenopausal women with early breast cancer.

After follow-up periods ranging from about 2 years to 5 years, there was a small 31 percent relative increase in cardiovascular adverse events with aromatase-inhibitor treatment compared with tamoxifen treatment.

On the other hand, the overall rate of all side effects, including blood clots and strokes, was somewhat higher among women given tamoxifen, the researchers point out.

The team concludes that, although the risk of cardiac events was increased with aromatase inhibitors, “it appears lower than was suspected previously.”

In summary, they say that this risk has to be balanced against the decreased risk of risk of blood clots and perhaps strokes, as well as improved survival free of breast cancer seen with aromatase inhibitors.

SOURCE: Cancer, January 15, 2008.