MRI Beats Mammogram for Women at High Risk

July 28, 2004 -- Women with a family history of breast cancer or genetic risk factors, such as BRCA mutations, may be better off with MRI breast cancer screening than with mammography, according to a new study.

Dutch researchers found MRI breast cancer screening was better at detecting tumors at an early stage among women at high risk for breast cancer due to hereditary or genetic factors. The results appear in this week's issue of The New England Journal of Medicine.

Women with a family history of breast cancer are at increased risk for the disease, and women with an inherited form of the BRCA1 or BRCA2 gene have the highest lifetime risk of breast cancer. These women develop breast cancer at an early age, yet mammograms in young women who have dense breast tissue can make screening mammograms less sensitive for detecting tumors.

MRI breast cancer screening uses magnetic resonance imaging to produce a highly detailed image of the breast. This imaging technique is not heavily influenced by breast tissue density to detect abnormalities.

Although MRI screening is very sensitive, researchers say it's not a viable option for widespread breast cancer screening due to the high cost, variations in technique, and the large number of false-positive results it produces. MRI breast cancer screening is currently used as a supplement to mammography in women at high risk for developing breast cancer.

Plusses and Minuses of MRI Breast Cancer Screening

In the study, researchers screened 1,900 women in the Netherlands who had a 15% or greater lifetime risk of breast cancer because of a family history of breast cancer or genetic risk factors, such the BRCA1 or BRCA2 mutation. The women were screened every six months with a clinical breast exam and once a year by MRI and mammography.

Over the course of nearly three years, a total of 51 breast cancer tumors were detected.

For all invasive breast cancers found in the study, researchers found MRI was better at detecting tumors than other methods, with a sensitivity of 80% compared with 18% for clinical breast examination and 33% for mammography.

For example, MRI detected 20 invasive cancers that were not found by mammography or clinical breast examination.

However, researchers found MRI was less specific than mammography in determining which tumors were cancerous (90% vs. 95%).

"A drawback of MRI screening is that it has a lower specificity than mammography, and as a result, MRI will generate more findings judged as uncertain, which require short-term follow-up or additional investigations," write researcher Mieke Kriege, MSc, of the Rotterdam Family Cancer Clinic, in the Netherlands, and colleagues. "In our study, screening by MRI led to twice as many unneeded additional examinations as did mammography (420 vs. 207) and three times as many unneeded biopsies."

Breast Cancer Screening Method Depends on Risk

In an editorial published in the same journal, Laura Liberman, MD, of Memorial Sloan-Kettering Cancer Center in New York, says this study provides additional evidence that MRI can detect otherwise hard-to-find breast cancers in women at risk for breast cancer, particularly those at highest risk, such as women with BRCA mutations.

However, no data supports the use of MRI in screening women at normal risk of the disease, says Liberman.

"Further outcomes research is essential to develop evidence-based recommendations for methods of breast cancer screening that are tailored to the specific needs of women at various levels of risk," writes Liberman.