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.
Bowles and her colleagues evaluated 12,500 women diagnosed with invasive breast cancer from 1999 through 2007 in eight different health systems.
The risk of heart failure was 1.4 times higher in those treated only with an anthracycline at the five-year mark. That was about the same increase as those treated with other types of cancer drugs.
However, those on Herceptin alone had more than four times the risk of heart problems compared to those who did not take the medication, the study stated.
And, the biggest increase in risk was seen in those on both anthracyclines and Herceptin. Those patients showed a sevenfold increased risk at the five-year mark, the researchers said.