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Huong Le-Petross, M.D., Assistant Professor, Department of Diagnostic Radiology |
Mammography has been the only imaging modality used for breast cancer screening for the past 30 years and has resulted in at least a 30% reduction in the breast cancer–related mortality rate in women. However, in the women at high risk of breast cancer, annual screening mammography has low sensitivity. In young women at high risk, the greater density of their breast tissue may make it difficult to detect cancer early. Also, in women with inherited risks, such as carriers of BRCA mutations, tumors tend to grow faster than in non-carriers.
Most women at risk for hereditary breast cancer opt for intensive breast screening rather than bilateral mastectomies. For these women, there is a definite need for additional imaging modalities to detect cancer earlier. In six prospective studies, the addition of annual contrast-enhanced magnetic resonance imaging (CE-MRI) to mammography was compared to clinical breast examination, mammography, and/or ultrasonography. The studies indicated that CE-MRI in combination with mammography offers the best screening option for women at high risk.
The revised American Cancer Society guidelines for breast screening published in May of this year recommend MRI with mammography in patients who have a lifetime breast cancer risk of 20–25%. This includes women who have an inherited risk for breast cancer and first-degree relatives of a BRCA mutation carrier. However, the most appropriate screening intervals for these high-risk women are not clear because of a lack of good data. At M. D. Anderson, high-risk patients are screened every 6 months, alternating between mammography and CE-MRI.
However, CE-MRI is not recommended as a screening tool for women with low to average breast cancer risk. This is partly due to technical limitations—a high false-positive rate is associated with MRI, and this rate may be even higher in the general population than in the high-risk population. (This recommendation may change as the technology matures.) Other drawbacks include the cost of an MRI exam and the added cost of follow-up studies.
It’s also important to remember that, while CE-MRI is a beneficial adjunct to mammography and clinical breast exam in high-risk women, CE-MRI should not replace screening mammography. To date, no hard data are available to show whether breast MRI used as an adjunct to mammography affects the breast cancer–related mortality rate in the high-risk population. The limitations of MRI should be communicated to each patient and a screening plan individually tailored.For more information on this topic or for questions about M. D. Anderson’s treatments, programs, or services, call askMDAnderson at (877) MDA-6789.
Other articles in OncoLog, December 2007 issue:
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Is MRI Better for Breast Screening? 
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