Two new studies support the need to monitor heart function among breast cancer patients receiving two common therapies. The findings are particularly important for women who have other risk factors for heart disease or cardiac dysfunction before treatment begins. The studies were published in the Journal of Clinical Oncology (JCO).

In the first study, researchers at M.D. Anderson Cancer Center in Houston found that 28% of women with advanced breast cancer who received trastuzumab (Herceptin) for a year or more experienced impaired heart function that could be reversed with medical treatment.

Among 218 patients with metastatic breast cancer who received long-term trastuzumab between 1998 and 2003 and were followed for nearly three years, 15.6% had a moderate reduction in left ventricular ejection fraction (LVEF, a measure of the heart's pumping ability) that did not cause any symptoms, and 10.9% developed impaired heart function that caused symptoms such as shortness of breath and fluid retention. One patient died of congestive heart failure. Women whose LVEF was lower than normal before therapy began were more likely to experience an impairment of heart function as a result of treatment.

"Long-term use of Herceptin appears to be safe, but some patients will experience cardiac toxicity. The good news is that this toxicity appears to be reversible with medical treatment such as beta-blockers and ACE inhibitors," explained Francisco Esteva, MD, Associate Professor of Medicine at M.D. Anderson and the study's senior author.