Herceptin (chemical name: trastuzumab) is a targeted therapy medicine used to treat HER2-positive breast cancer. Heart muscle damage and heart failure are potentially serious side effects of Herceptin.
A large study has found that older women diagnosed with early-stage, HER2-positive breast cancer treated with Herceptin have a higher risk of heart failure than women who didn’t get Herceptin. This higher risk also is higher than the risk reported in clinical trials on Herceptin.
The study was published online on Nov. 14, 2012 by the Journal of the American College of Cardiology. Read the abstract of “Incidence of Heart Failure or Cardiomyopathy After Adjuvant Trastuzumab Therapy for Breast Cancer.”
Doctors call treatments given after surgery to reduce the risk of the cancer coming back (recurrence) adjuvant treatments.
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 advanced-stage, HER2-positive breast cancers
- lower the risk of recurrence of early-stage, HER2-positive breast cancer with a high risk of recurrence
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 modest 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 45,537 women age 67 to 94 diagnosed with early-stage breast cancer in 2000 to 2007. Their anonymous medical records were in a U.S. database called the Surveillance, Epidemiology, and End Results (SEER) database for oncology.
The researchers grouped the women according to the treatments they received after surgery:
- Herceptin with or without chemotherapy that didn’t include an anthracycline (1% of the women)
- Herceptin plus anthracycline chemotherapy (0.9% of the women)
- anthracycline chemotherapy without Herceptin and with or without non-anthracycline chemotherapy (11.5% of the women)
- non-anthracycline chemotherapy (5.9% of the women)
- no chemotherapy or Herceptin (80% of the women)
The researchers found that Herceptin use went up over the time of the study:
- 2.6% of women got Herceptin in 2000
- 22.6% of women got Herceptin in 2007
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, which can lead to heart failure.
The researchers then looked to see how many women in each treatment group had developed heart disease or heart failure.
Compared to women who got no Herceptin and no chemotherapy after breast cancer surgery:
- women who got Herceptin had a 14% higher risk of heart failure or heart disease
- women who got both Herceptin and anthracycline chemotherapy had a 23.8% higher risk of heart failure or heart disease
- women who got anthracycline chemotherapy had a 2.1% higher risk of heart failure or heart disease
In clinical trials, Herceptin is reported to increase the risk of heart failure by 1.6% and increase the risk of heart disease by 7.2%. These lower numbers may be because the clinical trials included more younger women who didn’t have any other risk factors for heart disease, such as diabetes and high blood pressure.
The results suggest that heart problems related to Herceptin are more common in older women than many doctors think.
If you’re 67 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.