SUNDAY, June 3, 2007 (HealthDay News) -- The chances of developing congestive heart failure as a result of using Herceptin in early-stage breast cancer treatment does not increase over time, new research finds.
When added to standard chemotherapy, Herceptin (trastuzumab) reduces the risk of breast cancer recurrence by 52 percent after three years. The compound has proven to be effective in the 20 percent to 25 percent of breast cancer cases that test positive for the HER2/neu receptor.
But this benefit comes at a cost: 4.1 percent of people taking Herceptin developed heart failure over a three-year period, vs. 0.8 percent of patients who only received chemotherapy.
This latest study, reported Sunday at the American Society for Clinical Oncology meeting in Chicago, found that after five years, the incidence of heart failure was 3.8 percent.
"With an additional two years of follow-up for a cumulative five years, the incidence of heart failure in the available group numbers was essentially unchanged," said Dr. Priya Rastogi, assistant director of medical affairs for the National Surgical Adjuvant Breast and Bowel Project (NSABP), which oversaw the study. "There was a substantial recovery in cardiac function in all three groups who had clinically relevant declines in heart function."
Updated results on the drug's cardiac risk over time have also resulted in a risk profile that should help determine which patients might want to steer clear of Herceptin. For instance, women who were older, used hypertensive medications and had a low normal baseline left ventricular ejection-fraction (a measure of heart function) were more likely to develop heart failure while taking the drug.
"A model of prediction of risk for heart failure was developed that could support a more individualized assessment of cardiac risk," Rastogi, an assistant professor of medicine at the University of Pittsburgh Cancer Institute, said. "The choice of trastuzumab-containing regimens should be based on an individualized assessment of risk and benefit in women with HER2-positive breast cancer. We want to make this an easy formula for physicians to use. We're in the process of doing that."
In other good news out of the meeting for women with early-stage breast cancer, a British study found that delivering fewer but larger doses of radiation to women with early breast cancer is as effective as the conventional schedule of 25 doses in reducing the risk of recurrence, even though the total dose of radiation was lower.
"It's likely that patients can be effectively and safely treated to a lower total dose with fewer larger fractions [doses] than the current standard," said study author Dr. John Dewar, a clinical oncologist at the University of Dundee in Scotland. "This should encourage further studies and will help radiation oncologists individualize patients." Those further studies need to determine if recurrence rates stay low over time.
The main benefit of the approach, called hypofractionation, is that it is easier on the patient. It also resulted in fewer adverse changes in the appearance of patients' breasts.
"This is very exciting news for patients, as radiation is very disruptive to life," said Dr. Julie Gralow, the moderator of a news conference on the new research and an assistant oncology professor at the University of Washington in Seattle. "If we could achieve the same outcome with fewer trips to the radiation center, this would be a tremendous benefit for patients."
Another study presented at the meeting Sunday found magnetic resonance imaging (MRI) was better than mammography for detecting "high-grade" ductal carcinoma in situ (DCIS), a form of pre-invasive breast cancer. These lesions are most likely to progress to aggressive invasive cancer, and therefore need to be diagnosed early.
"High-grade DCIS is easily curable by resection, but, if left untreated, will progress to high-grade invasive cancer," said study author Dr. Christiane K. Kuhl, vice chairman and a radiology professor at the University of Bonn in Germany.
Forty percent of DCIS lesions were only found by MRI, and 78 percent of those were high grade, according to the study. On mammography, only 8 percent of DCIS were visible, and all but one were low grade.
The question is how quickly MRIs will be used for regular screening, or if they will be used at all. MRIs are routine in Germany, where the study was conducted, but not in the United States.
"MRI is a great tool when used in the right hands, but we don't have quality control anywhere in the world for MRI as we do for screening mammography," Gralow noted. "We hope soon to have a partial rectification of this, as the American College of Radiology is starting a voluntary accreditation program in the U.S. for breast MRI. At that point, it will be fair to say that programs that choose to undergo this accreditation are doing breast MRI in a similar manner. All breast MRIs are not the same. We need to have standards and reproducibility."
Kuhl added, "Our study proves that MRI is better. Whether we use MRI or mammogram is more a question of finances and availability than a medical question."
But there are other issues not considered in this study, said Dr. Stephen Sener, past president of the American Cancer Society. "The issue of whether MRI improves survival is not answered yet," he said.
There is also a high rate of false-positive results, he added, which can drive up costs as women go for additional tests.
The National Cancer Institute has more on Herceptin.