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June 3, 2007
After five years, the risk of congestive heart failure (CHF) associated with adding trastuzumab (Herceptin) to combination chemotherapy for early-stage breast cancer did not increase, according to a phase III clinical trial from the National Surgical Adjuvant Breast and Bowel Project (NSABP). CHF can cause symptoms such as shortness of breath and a reduction in the heart's pumping ability, as measured by the left ventricular ejection fraction (LVEF).
"We are encouraged by these new data showing no additional late heart problems associated with trastuzumab," said lead author Priya Rastogi, MD, Assistant Director of Medical Affairs for the NSABP and Assistant Professor of Medicine at the University of Pittsburgh Cancer Institute in Pennsylvania. "While we still need to check patients closely for side effects to the heart, this is reassuring news for women taking this drug."
Trastuzumab works by blocking the human epidermal growth factor receptor 2 (HER2), which is present in unusually high levels in approximately 20% to 25% of women with breast cancer. Previous studies showed that adding trastuzumab to chemotherapy for women with early-stage HER2-positive breast cancer lowered the risk of the return of breast cancer by 52% after three years compared with chemotherapy alone. One of these studies from the NSABP showed that the occurrence of CHF at three years was 4% for the women taking trastuzumab, compared with 0.8% of women who did not receive trastuzumab.
As part of the NSABP clinical trial, women with HER2-positive breast cancer that had spread to the lymph nodes received either doxorubicin (Adriamycin, Rubex) and cyclophosphamide (Cytoxan, Neosar), followed by paclitaxel (Taxol), or the same treatment plus trastuzumab. The occurrence of CHF was compared between the two groups (1, 850 women in total).
After five years, the occurrence of CHF remained at 4% for the women who received trastuzumab. The researchers also observed an improvement in LVEF over time among women in the trastuzumab group who experienced an initial decline in heart function.
What This Means for Patients
In this study, heart failure occurred in 4% of women with breast cancer who were treated with trastuzumab. Some factors that increased a woman's risk of heart failure included being age 50 or older, a low to normal LVEF, and high blood pressure. Women with breast cancer should talk with their doctors about their risk factors for heart problems to help make appropriate breast cancer treatment decisions.