Use of MRI in Breast Cancer Remains In Flux

The use of magnetic resonance imaging (MRI) in finding and treating breast cancer has been a source of controversy. Although the appropriateness of many uses of this imaging technique remains unsettled, a consensus has formed outlining recommendations utilizing MRI of the breast as a screening adjunct to mammography.

In March 2007, the American Cancer Society Breast Cancer Advisory Group issued new breast cancer screening recommendations that for the first time included yearly MRI scanning along with mammography for women aged 30-69 who have an estimated lifetime risk of 20% or more of developing breast cancer. Those with risk estimates between 15% and 20% fell into a grey area where the Group was unable to come to a consensus. Those whose lifetime risk was 15% or less did not benefit from the additional screening.

“The reason for these suggestions has to do with the specificity and sensitivity of MRI breast imaging,” said Stephen Grobmyer, MD, from the division of surgical oncology in the department of surgery at the University of Florida in Gainesville. “It is very sensitive, but not very specific. While MRI can find many cancers that other methods miss, they also find a lot of things that are not cancers.”

The clinical guidelines, therefore, balance the cost of the procedure (between $1,000 and $1,500) and the possibility of false positives against the likelihood that cancer may be missed using only mammography.

There are some early indications that MRI-guided biopsies may lessen the concerns about false positives. The extra sensitivity of magnetic resonance imaging was finding abnormalities that were too small to see by other methods.

“In the old model, we would see things on MR and were forced to act on them even though we did not know if it was cancer unless we operated,” said Grobmyer. “With MR-guided biopsies, we can work up these lesions before defining what the definitive therapy should be. This can make the difference deciding between a partial or complete mastectomy.”

Other uses being explored

Although there are no official clinical guidelines, many experts suggest there are times when using MRI of the breast is appropriate to help with diagnosis and management of the disease.

“Patients with a palpable mass or multifocal disease should be considered candidates for MRI,” said Jame Abraham, MD, medical director of the Mary Babb Randolph Cancer Center and associate professor of medicine at West Virginia University in Morgantown. “When the mammogram is not very clear and the breast tissue is very dense, I would go ahead and do the additional studies.”

Additional diagnostic indications would include patients presenting with axillary metastasis where conventional methods do not show the primary lesion.

“MRI is accepted as a way to look for the primary lesion in these patients,” said Grobmyer. “About 50% of the time, MRI will find cancers that were not seen by other imaging studies.”

Treatment planning

Magnetic resonance imaging may be useful in treatment planning and follow-up. For example, MRI of the breast is one method to assess neo-adjuvant chemotherapy treatment at baseline and the end of each cycle.

The use of magnetic resonance in surgical intervention is much more controversial. It might prove to be useful in getting a more precise estimate of the size and placement of the tumor.

“Our published research suggests that there is a benefit,” says Grobmyer. “We think it gives a more accurate estimate of tumor size and helps locate otherwise unknown sites of disease.” He notes that others have suggested using MRI in this manner may lead to overtreatment and unneeded interventions. In addition, conventional therapy has such a low rate of local recurrence that any gains are felt to be marginal and very expensive.

Quality assessment remains a concern

Both experts agree that getting useful results from a breast MRI can be difficult. There is a very high learning curve for the staff that administers and interprets the test. In addition, specialized coils and other equipment are needed to obtain a test that provides useful information.

“Criteria for quality in breast MRI just isn’t out there yet so it is hard to lay down any strict ways to assess this,” said Grobmyer. “It is important that those doing cancer care have confidence in the people they are working with. How that is defined is currently an individual decision.”

Overall, both physicians think that the impact of magnetic resonance in breast health will continue to increase in importance. Increases in knowledge and advances in technology will fuel these changes. However, it is also important to remember the system’s challenges.

“Some people seem to think that breast MRI is the ultimate answer to every question, and that is clearly not the case,” said Abraham. “This imaging technique will continue to be an addition to mammography and will not replace it any time soon. Even though we are trying to embrace this new technology, we should always be cautious about its limitations.”