Breast cancer drug may raise heart risk

Women with breast cancer who are treated with the cancer drug Herceptin may have more long-term cardiac problems than experts have thought, new research suggests.

It has been known that women treated with anti-cancer drugs known as anthracyclines and Herceptin (trastuzumab) are at higher risk for heart failure and cardiomyopathy, a weakening of the heart muscle. But that information has come primarily from clinical trials, which typically exclude women 70 and older and those with coexisting chronic diseases, researchers noted.

"The risk of heart failure associated with these drugs might be higher than what has been shown in clinical trials," explained study author Erin Aiello Bowles, an epidemiologist at Group Health Research Institute in Seattle. Her report was published online Thursdayin the Journal of the National Cancer Institute.

Bowles evaluated 12,500 women with invasive breast cancer from 1999 through 2007 in eight different health systems. The patients' average age was 60. Follow-up time ranged from more than two years to nearly seven. The researchers tracked the type of cancer treatment and diagnoses of cardiac problems. The risk of heart failure was 1.4 times higher in those treated only with an anthracycline at the five-year mark, about the same increase as those treated with other drugs. However, those on Herceptin alone had more than four times the risk of heart problems compared with those who did not take it, the study stated.

The biggest increase in risk was in those on both medications. Those patients showed a sevenfold increased risk at the five-year mark, researchers said.