WASHINGTON – While the use of magnetic resonance imaging as a screening tool for breast cancer has increased significantly over the past decade, there is still little evidence of its clinical benefits and cost-effectiveness, according to a panel of experts who addressed a capacity crowd at the annual clinical congress of the American College of Surgeons.
Dr. Monica Morrow
Patients at high risk of developing breast cancer (e.g., those with BRCA mutations or a greater than 20% risk of developing breast cancer during their lifetime) could benefit from breast MRI. The panel, however, pointed to a wide range of U.S., Canadian, and European studies showing that there is no evidence that MRI improves breast cancer survival, and it increases the rate of mastectomies. The panel members included Dr. Elisa R. Port and Dr. Monica Morrow, both of Memorial Sloan-Kettering Cancer Center in New York, Dr. Isabelle Bedrosian of MD Anderson Cancer Center in Houston, and Dr. Richard J. Bleicher of Fox Chase Cancer Center in Philadelphia.
The American Cancer Society and the National Comprehensive Cancer Network have developed MRI screening guidelines to distinguish which groups of patients should or should not be screened. However, there are very few data thus far to indicate just when to start or stop screening, or how often to perform screening, said Dr. Bedrosian.
“There are no data on the impact of MRI screening on survival outcomes,” she said, noting that the data to support MRI screening in terms of outcomes are based on disease stage migration, not survival.
She added that there are very few data about the cost-effectiveness of breast MRI screening. Patient age, BRCA gene mutations, breast density, and the cost of MRI must all be factored into the cost-effectiveness of MRI screening. The data show that MRI screening is more cost effective for higher-risk patients, but the panel wondered whether breast MRI screenings could be contributing to the nation’s rising health care costs.
There are currently 70 million women in the United States between the ages of 30 and 70. Of those, 1% are at high risk of developing breast cancer and are eligible for screening, which translates to a potential 1 million MRI screenings per year, said the panel.
“The most troubling finding is that it causes us to think about breast cancer the way we thought about it in the 1970s, the 1980s, and the early 1990s – that the disease burden in the breast is the sole or primary determinant of breast cancer outcome,” said Dr. Morrow. “The modern era tells us that’s really not true.”
In addition, she mentioned two retrospective studies (one in the United States and the other from the Netherlands Cancer Institute) that showed no decrease in unplanned mastectomy for patients who had preoperative MRI.
To answer the question of whether or not obtaining an MRI increases the likelihood of obtaining negative margins, Dr. Morrow summarized the results of four retrospective studies involving more than 2,500 patients. “The studies showed no statistically significant benefit in terms of reducing positive margins with MRI,” she said.
Another prospective randomized trial of 1,600 women showed that the net effect of MRI was a slightly higher rate of mastectomy in patients who had an MRI preoperatively, but no reduction in the need for further surgery.
Dr. Morrow added that in patients who have unifocal cancer, MRI can’t underestimate the extent of disease but instead overestimates the extent of disease in a third of the patients. In the case of multifocal or multicentric disease, MRI is accurate in a third of the patients, it overestimates the disease in another third, and it misses the disease a third of the time.
“There’s no possibility that MRI will improve breast cancer survival,” Dr. Morrow said. It takes a difference in local failure rates of greater than 10% at 5 years post treatment to see a survival difference in 15 years, she added. “Current rates of local recurrence at 10 years are less than 10%, and there should be no expectation that MRI will change survival.”
Medicare data show that the number of MRIs (all types) performed has increased over the past decade. While the total cost of treating breast cancer patients in the United States is increasing at 4% per year, the imaging costs are increasing at 10% a year, said Dr. Bleicher.
Although there are no national data showing what percentage of health care costs is attributable to breast MRIs, “one of the things that’s not in dispute [is that] breast MRI usage in breast cancer patients is increasing,” and its contribution to rising health care costs is “highly suggestive,” he added.