Roughly one in four breast cancers has too much of a protein called HER2, which makes the cancer grow faster. The medication Herceptin (trastuzumab) targets the HER2 protein to help breast cancer patients live longer. But this medication may be linked to heart problems.
A new study has shown that older breast cancer patients taking Herceptin had higher risks of congestive heart failure than patients who didn’t take the medication.
Congestive heart failure occurs when the heart muscle doesn’t pump blood as well as it should.
Other factors, the researchers learned, also contributed to the increased congestive heart failure risks in those who took Herceptin.
Mariana Chavez-MacGregor, MD, MSc, assistant professor of breast medical oncology at The University of Texas MD Anderson Cancer Center, was the lead investigator of this study that evaluated the rates of and risk factors associated with Herceptin-related congestive heart failure (CHF) in older patients.
About 25 percent of breast cancers make too much human epidermal growth factor receptor 2 (HER2). These tumors tend to grow faster and are more likely to come back (recur) than tumors than that don’t overexpress HER2.
Herceptin is intended to improve the outcomes of HER2-positive breast cancer patients when given with chemotherapy following surgery, but it is also known to increase the risk for heart problems.
Dr. Chavez-MacGregor and colleagues used the Surveillance, Epidemiology, and End Results (SEER) Medicare and Texas Cancer Registry–Medicare databases to identify patients 66 years of age or older diagnosed with breast cancer between 2005 and 2009.
A total of 9,535 patients were included, 2,203 of whom had received Herceptin. The median age was 71.
After reviewing patient data, the researchers discovered that 29.4 percent of the patients who had taken Herceptin developed CHF, compared to 18 percent of patients who had not been given the medication.
Herceptin users were 95 percent more likely than non-users to develop CHF.
The study revealed other factors that increased CHF risks among those who took Herceptin:
- 80-year-old patients had a 53 percent increased risk of CHF compared to patients aged 66 to 79.
- Coronary artery disease and other heart problems increased CHF risks by 82 percent compared to patients with no heart problems.
- Hypertension increased the risk of developing CHF by 24 percent compared to patients with no hypertension.
- Taking Herceptin weekly increased CHF risks by 33 percent compared to receiving the medication every three weeks.
The authors noted that Herceptin-related CHF risks found in this study were higher than those reported in clinical trials.
Adam Brufsky, MD, PhD, professor of medicine at the University of Pittsburgh School of Medicine, told dailyRx News, "This article does raise concern about the use of Herceptin in older woman with breast cancer, and we need to pay attention to cardiac symptoms in these women."
“It is possible that among high-risk patients, early cardiology referral, the use of prophylactic cardioprotective agents, and close monitoring may be beneficial,” the authors of this study concluded.
This study was published October 14 in the Journal of Clinical Oncology.
The research was supported by the Center for Comparative Effectiveness Research on Cancer in Texas, a multi-university consortium funded by the Cancer Prevention and Research Institute of Texas, the Nellie B. Connally Breast Cancer Research fund and the American Cancer Society.
One of the authors serves as a consultant to several pharmaceutical companies and receives research support from another. No other conflicts of interest were reported.