Breast MRI poises for surge from new guidelines and research

Two developments this week are expected to give a big boost to breast MRI utilization. Updated American Cancer Society guidelines advise adding annual breast MRI to screening in very high-risk women. And a massive new American College of Radiology Imaging Network trial has documented MRI's value in assessing women with cancer in a single breast to detect or rule out disease in the opposite breast.

The ACS guidelines, published on March 28, say women with the following characteristics should undergo annual breast MRI screening:

• BRCA1 or BRCA2 mutation or first-degree relative with these mutations

• lifetime risk of breast cancer 20% to 25% or greater

• radiation to the chest between the ages of 10 and 30

• Li-Fraumeni syndrome, Cowden syndrome, or Bannayan-Riley-Ruvalcaba syndrome, or possibility of having one of these syndromes based on history in first-degree relative

There is not enough evidence currently to support breast MRI screening in women with a personal history of breast cancer or ductal carcinoma in situ or in those who have extremely dense breasts, according to the guidelines.

For women who have been recently diagnosed with cancer in one breast, MRI is extremely useful in detecting and ruling out mammographically occult cancer in the contralateral breast, according to a large new multicenter study conducted by the ACRIN.

Research was funded by the National Cancer Institute, and results are set to be published on March 29 by The New England Journal of Medicine (NEJM 356;13:1295-1313).

In comparison with previous reports in the literature, the new study involving 25 centers and almost 1000 women found better performance for breast MRI in women who have had cancer in one breast, with sensitivity of 91% and specificity of 88%. Negative predictive value was extremely high at 99%, while positive predictive value was just 21%, and the use of breast MRI resulted in an increase in biopsies of benign lesions. Since the study included diverse community and academic sites, results could be generally reproducible.

The value of breast MRI in assessing high-risk women, including those who have had a diagnosis of cancer, is a hot topic. Patients who have had cancer may also have disease in the opposite breast that is not detected with mammography or clinical examination.

Consequently, some women opt for an elective mastectomy in the opposite breast as a preventive measure for cancer. Others are diagnosed with cancer in the contralateral breast at a later date and then subjected to a second round of cancer treatment. With its high negative predictive value, breast MRI at the time of the initial diagnosis could reassure patients of the absence of additional disease and act as a guide to the most appropriate treatment, the study said.

The 969 women involved in the ACRIN study had no signs of cancer on mammography or physical examination and underwent breast MRI within 60 days of diagnosis. They were followed for one year. Biopsy was recommended in 135 women and performed in 121, based on MRI results. Cancer was detected by breast MRI in 30 women, and the rest of the biopsies were negative. Mean tumor size was 10.9 mm, and a substantial number of detected cancers were invasive. Another three cancer cases were not detected by MRI.

The authors suggested that evidence supporting MRI in women who have been diagnosed with cancer in one breast is compelling, but they also stressed that the findings should not be taken as a sign that the general female population needs a breast MRI.

For more information from the Diagnostic Imaging archives:

Breast MRI pays its way in preoperative planning

Breast MRI's future depends on finding suitable indications

MRI tops CT in detecting intraductal cancer