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New guidelines from the American Cancer Society (ACS; Atlanta) suggest that women considered at high-risk for breast cancer should undergo screening with MRI scans. This group is defined as women considered to have about a 20% to 25% or greater than normal risk of cancer.

The ACS guidelines, suggested as an adjunct to mammography, were published Wednesday in the March/April 2007 issue of CA: A Cancer Journal for Clinicians.

A study with results reported in the March 29, 2007, issue of the New England Journal of Medicine found that MRI scans of women who were diagnosed with cancer in one breast detected more than 90% of cancers in the other breast that were missed by mammography and clinical breast exam at initial diagnosis.

The NEJM study, which showed that adding an MRI screen in high-risk women "effectively doubled" the number of cancers immediately found in the other, or contralateral, breast, was sponsored by the American College of Radiology Imaging Network (ACRIN; Philadelphia) and supported by the National Cancer Institute, part of the NIH.

According to ACRIN, the hope is that, due to the finding of a MRI's strong ability to predict the absence of a breast tumor, it may be possible for women to avoid unnecessary mastectomies and have "more reassurance" that the opposite breast is free of cancer.

"One in 10 women diagnosed with cancer in one breast will develop the disease in the opposite breast. Having a better technique to find these cancers as early as possible will increase the chances of successful treatment," said Elias Zerhouni, MD, director of NIH.

The ACRIN trial was designed to determine whether the use of MRI could improve upon clinical breast exam and mammography in detecting breast cancer in the opposite breast at the time of the initial breast cancer diagnosis.

The study recruited 1,007 women, from 25 institutions, who had a recent diagnosis of cancer in one breast. Of these, 969 women completed the study, begun in April 2003. All of the women enrolled had a negative mammogram and negative clinical breast exam of the opposite breast within 90 days prior to the MRI.

After receiving an MRI, 33 contralateral breast cancers were diagnosed in the study. Thirty of these tumors, or 91%, were diagnosed as a result of MRI. The other three cancers were detected due to subsequent mastectomies. Researchers found that the added benefit of MRI was consistent, regardless of a woman's cancer type, age, or breast density. Dense breasts have more glandular and connective tissue as well as less fat tissue.

To develop the new guidelines fir breast cancer detection — which had not been updated since 2003 — an expert panel of 15 members "reviewed and discussed data during a series of conference calls and working meeting in August 2006." The panel made its recommendations based on literature related to breast MRI screening published between September 2002 and July 2006.

According to the ACS, MRI uses magnetic fields to produce cross-sectional images of tissue structures.

Perhaps the most difficult aspect of the new guidelines will be among women as they try to answer the question, "Do I fall into a high-risk category.

The ACS recommendations for breast MRI screening as an adjunct to mammography, based on evidence, call for:

  • annual MRI screens for women with either the BRCA1 or BRCA2 gene mutations;
  • being a first-degree relative of BRCA carrier, even if a woman has not been tested for the gene mutation herself.
  • women who have a lifetime risk of 20% to 25% or greater, as defined by models based on family history.

The ACS guidelines referenced several models available for clinicians to determine a woman's lifetime risk.

Based on "expert consensus opinion," the new guidelines also call for annual MRI screening for women who received radiation to their chest between the ages of 10 and 30, due to Hodgkins disease. Additionally, it calls for screening in women with Li-Fraumeni syndrome or in first-degree relatives, that is, women with a mutation in the TP53 gene, as well as Cowden and Bannayan-Rile-Ruvalcaba syndromes and first-degree relatives, or women with a mutation in the PTEN gene.

The panel decided there was "insufficient evidence" to recommend for or against MRI screening in women with a lifetime risk of 15% to 20%. The same was true of women with the following conditions: lobular carcinoma in situ; atypical ductal hyperplasia; extremely dense breasts on mammography; or women with a personal history of breast cancer, including ductal carcinoma in situ.

For women considered to have less than a 15% lifetime risk of developing breast cancer, the panel recommended against MRI screening.

However, one panel member stressed that MRIs should be an addition to – not a replacement of – mammography.

Etta Pisano, MD, of the University of North Carolina (Chapel Hill, North Carolina), in an interview with the Associated Press, said, "The take-home message of our paper is not, "Don't get mammography.' It's 'Get MRI and mammography.'"

The Susan G. Komen Foundation (Dallas), focused on breast cancer prevention and treatment, issued a statement saying that while MRI is known to be more sensitive than mammography and can find smaller tumors, its specificity creates concerns: specifically, that MRI screening will create more false positives, which could lead both to additional unnecessary testing and additional biopsies. It also noted the much higher cost for MRI vs. mammograms.

"The importance of developing more and better tools for early detection cannot be underestimated," said Cheryl Perkins, MD, senior clinical advisor for the foundation.

But she added: "No single technology is perfect. It is the combined use of screening options available today that will result in the best chances for early detection."

The foundation also noted that radiologists must be specifically trained in MRI.

The ACS guidelines also noted that MRI breast screening requires "appropriate techniques and equipment, together with experienced staff" and that MRI breast screening should be completed with equipment designed especially for that purpose, as opposed to MRI devices with body, chest or abdominal coils.

In its response to the new guidelines, Aurora Imaging Technology (Andover, Massachusetts), the developer of an FDA-cleared MRI system specifically designed for breast imaging, said that its network of Aurora 1.5T Dedicated Breast MRI System is "well poised" to meet the expected increased demand for MRI breast screening. The company reports systems installed in 23 locations throughout the U.S., Europe and Asia.

"While the response to [Wednesday's] news may create a sudden surge of demand for breast MRI, our Aurora users have already seen a rapid growth in patient demand . . . ," said Olivia Ho Cheng, president/CEO of Aurora.

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