Herceptin (chemical name: trastuzumab) is a targeted therapy medicine used to treat HER2-positive breast cancer. Heart muscle damage and heart failure are serious possible side effects of Herceptin.
A large study suggests that older women diagnosed with early-stage, HER2-positive breast cancer treated with Herceptin have a higher risk of heart failure than similar women who weren’t treated with Herceptin. This higher risk also is higher than the risk of heart failure reported in clinical trials on Herceptin.
The study was published online on Oct. 14, 2013 by the Journal of Clinical Oncology. Read the abstract of “Trastuzumab-Related Cardiotoxicity Among Older Patients With Breast Cancer.”
HER2-positive breast cancers make too much of the HER2 protein. The HER2 protein sits on the surface of cancer cells and receives signals that tell the cancer to grow and spread. About one out of every four breast cancers is HER2-positive. HER2-positive breast cancers tend to be more aggressive and harder to treat than HER2-negative breast cancers.
Herceptin works by attaching to the HER2 protein and blocking it from receiving growth signals. Herceptin, which is given intravenously, is approved by the U.S. Food and Drug Administration to:
- treat metastatic, HER2-positive breast cancers
- treat earlier stages of HER2-positive disease as adjuvant treatment (treatment after the initial treatment, such as surgery), either alone or as part of a regimen with chemotherapy
Women treated with Herceptin may have side effects, including:
- high blood pressure
- joint and back pain
- hot flashes
Some women on Herceptin will have a small drop in heart function during treatment. In some cases, heart failure develops. Heart function can recover when Herceptin treatment stops.
Other research has shown that Herceptin is more likely to cause heart problems in:
- older women
- women with diabetes
- women with preexisting cardiovascular risk factors such as high blood pressure, high cholesterol, and obesity
In this study, researchers looked at the medical records of more than 9,500 women age 66 or older diagnosed with early-stage (stage I-III) breast cancer between 2005 and 2009. Half of the women were older than 71 and half the women were younger. The women’s anonymous medical records were in a U.S. database called the Surveillance, Epidemiology, and End Results (SEER) database for oncology.
The researchers found that 2,203 of the women (23.1%) were treated with Herceptin.
Women treated with Herceptin were more likely to develop heart failure than women not treated with Herceptin. Rates of heart failure were:
- 29.4% in women treated with Herceptin
- 18.9% in women who didn’t get Herceptin
In the women treated with Herceptin, certain factors seemed to increase the risk of heart failure, including:
- older age (being older than 80)
- damaged or diseased coronary arteries
- high blood pressure
- getting Herceptin weekly (Herceptin is usually given every week but can sometimes be given on a 3-week schedule)
In clinical trials, Herceptin is reported to increase the risk of heart failure by 1.6%. This lower number may be because the clinical trials included more younger women who didn’t have any other risk factors for heart disease, such as coronary artery disease and high blood pressure.
The results suggest that heart problems related to Herceptin are more common in older women than many doctors think.
It’s important to know that this study didn’t look at whether the women who got Herceptin also got an anthracycline chemotherapy medicine after surgery. An anthracycline chemotherapy medicine is typically part of the combination used to treat HER2-positive breast cancer. Adriamycin (chemical name: doxorubicin) and Ellence (chemical name: epirubicin) are anthracyclines. Like all chemotherapy medicines, anthracyclines may cause serious side effects, including heart damage that can lead to heart failure.
If you’re 66 or older and have been diagnosed with HER2-positive, early-stage breast cancer, you may want to ask your doctor about this study if Herceptin and/or anthracycline chemotherapy will be part of your treatment plan. It’s a good idea to ask your doctor about your personal risk of treatment-related heart damage and whether or not visiting a cardiologist before treatment starts is a good idea for you. The cardiologist can evaluate your heart function and decide if you’re at high risk for developing heart disease or heart failure from breast cancer treatment. You also may want to ask your oncologist how your heart function will be monitored during treatment.
Together, you can decide on the best treatment plan for your unique situation.