Alexandria, VA--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 will be published online August 14 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.
In an accompanying editorial, Daniel Hayes, MD, of the University of Michigan Comprehensive Cancer Center, and Michael H. Picard, MD, of Massachusetts General Hospital, wrote, "Careful and frequent monitoring of patients treated with trastuzumab should include a history and physical examination in addition to non-invasive imaging of ventricular function."
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In the second study, University of Pennsylvania researchers found that women with early stage breast cancer who received radiation therapy to the left side of the chest were more likely than those who received right-sided radiation to develop heart disease during the subsequent two decades. However, left-sided radiation therapy did not increase the risk of death from a heart-related problem.
"Our findings showed that radiation therapy in patients with cancer in the left breast has a small but finite risk of coronary artery disease that may not show up for more than ten years after treatment," said lead author Eleanor Harris, MD, who is now Associate Professor and Clinical Director of Radiation Oncology at the H. Lee Moffitt Cancer Center & Research Institute in Tampa, Florida. "Women receiving radiation to the left side of their chest need to be aware of this risk, and take the appropriate steps to monitor their cardiovascular health."
Dr. Harris and her colleagues compared heart disease incidence and mortality between 477 women with right-sided early-stage breast cancer and 484 women with left-sided breast cancer who were treated with contemporary radiation oncology techniques (which are more targeted than older approaches) between 1977 and 1994, and were followed for up to 20 years. The rate of death from a cardiac cause was similar between the two groups (6% for the left-sided group versus 4% for the right-sided group).
However, more women who received radiation to the left side of the chest developed coronary artery disease (25% versus 10%) or had a heart attack (15% versus 5%). Moreover, having high blood pressure before therapy increased the risk of heart disease associated with radiation therapy in the left-sided group. Dr. Harris noted that recent advances in radiation techniques allow more accurate monitoring of heart volumes, and that further reductions in the amount of heart tissue receiving radiation during treatment for left-sided breast cancer are achievable.
In an accompanying editorial, Abram Recht, MD, of Harvard Medical School and Beth Israel Deaconess Medical Center, noted that studies evaluating the effects of left-sided radiation on heart disease risk have reported different findings, and that the effects of anti-cancer drugs that may damage the heart (such as anthracyclines) should also be considered. However, he encouraged women who receive radiation therapy to the left side of the chest to be sure to have regular screenings for cardiac risk factors. "I strongly encourage patients to vigorously treat high blood pressure and high cholesterol, and to avoid smoking," he noted.
"Long-Term Cardiac Tolerability of Trastuzumab in Metastatic Breast Cancer: The M.D. Anderson Cancer Center Experience." Valentina Guarneri, et al, The University of Texas M.D. Anderson Cancer Center, Houston, TX.
"Heart of Darkness: The Downside of Trastuzumab." Daniel F. Hayes, University of Michigan Comprehensive Cancer Center, Ann Arbor, MI and Michael H. Picard, Massachusetts General Hospital and Harvard Medical School, Boston, MA.
"Late Cardiac Mortality and Morbidity in Early-Stage Breast Cancer Patients After Breast-Conservation Treatment." Eleanor Harris et al, University of Pennsylvania School of Medicine, Philadelphia, PA.
"Which Breast Cancer Patients Should Really Worry About Radiation-Induced Heart Disease--And How Much?" Abram Recht, Harvard Medical School and Beth Israel Deaconess Medical Center, Boston, MA.
A consumer information piece on this study can be found on ASCO's patient website at the time of embargo lift at, People Living With Cancer.org, at www.plwc.org/CancerAdvances. Please refer your readers to www.plwc.org/breast for comprehensive information on coping with, diagnosing, and treating breast cancer.
The Journal of Clinical Oncology is the semi-monthly peer-reviewed journal of the American Society of Clinical Oncology (ASCO), the world's leading professional society representing physicians who treat people with cancer.
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Journal of Clinical Oncology