Magnetic resonance imaging (MRI) may be helpful as a breast cancer screening tool for women at high risk of developing breast cancer and can be used to help guide surgical treatment of the cancer.1
MRI Screening for Breast Cancer
MRI uses radio waves and a magnet to create detailed images of the inside of the body and has several advantages over conventional mammography. The American Cancer Society now recommends that women at high risk of breast cancer undergo yearly breast cancer screening with breast MRI in addition to mammography. These recommendations were prompted by several studies of MRI screening of women at high risk of breast cancer.
Advantages of MRI
- Avoids the use of ionizing radiation
- Images the entire breast volume and chest wall
- Superb 3-D lesion mapping with accurate size estimation for invasive carcinoma
- Detects occult, multifocal, or residual malignancy
- Ability to image regional lymph nodes
MRI More Sensitive than Mammography for Women at High-Risk of Breast Cancer
According to research published in The New England Journal of Medicine, MRI is more sensitive than mammography in the detection of early breast cancer in women at a high risk of developing the disease, including those with BRCA1 and 2.3,4
Researchers associated with the Magnetic Resonance Imaging Screening Study Group conducted a clinical trial to directly compare MRI to mammography in the detection of early breast cancer. This trial included 1,909 women who were considered to be at a high risk of developing breast cancer either due to specific genetic mutations or a strong family history of breast cancer. The women were screened every 6 months with a clinical breast examination and every year with mammography and MRI. The results from mammography and MRI were read independently. At approximately 3 years of follow-up, the percentage of breast cancers detected were 17.9% for clinical breast examination, 33.3% for mammography, and 79.5% for MRI. The ability to distinguish a suspicious result between cancer and a benign mass was 98.1% for clinical exam, 95% for mammography, and 89.8% for MRI.
The researchers concluded that MRI is a more sensitive screening method than mammography in women at a high risk of developing breast cancer. However, MRI is less able to distinguish between cancer and benign tumors, leading to a higher rate of unnecessary biopsies which is why it is recommended for those at high risk and not for women at normal risk of developing breast cancer.
National Comprehensive Cancer Network (NCCN) guidelines on MRI Screening
- Annual MRI screening recommended in first-degree relatives of a BRCA carrier, but untested (encourage genetic testing before MRI)
- Annual MRI screening is recommended for women with lifetime risk 20% or greater, as defined by models that are largely dependent on family history. Encourage genetic testing for first-degree relatives. If testing declined, recommend MRI.
- Annual MRI screening is recommended for women who received radiation therapy to the chest when aged 10-30 years.
In addition to its role in the screening of women at high risk of breast cancer, MRI may also play a role in the evaluation of women with newly diagnosed breast cancer.
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MRI for Evaluation of Breast Cancer
MRI can also be used to evaluate the extent of disease in women with newly diagnosed breast cancer. Results from MRI prior to surgery may identify multiple areas of cancer within a breast more accurately than standard mammography in women with early breast cancer. These results may ultimately play a significant role in making appropriate treatment choices for patients with this disease.
According to several studies the use of MRI before breast surgery identifies multi-focal cancers in roughly 10% of women with newly diagnosed breast cancer. This changed surgical management from lumpectomy to mastectomy. MRI may also resulted in unnecessary changes to surgical plans.2,5,6
The Journal of the National Comprehensive Cancer Network summarized what is known about breast MRI in women with newly diagnosed breast cancer and provided recommendations regarding the use of MRI in this setting. Some of the key points are as follows:
- When MRI is used, it should be used in addition to (not in place of) other standard approaches to imaging such as mammography and ultrasound.
- A potential benefit of MRI among women with newly diagnosed breast cancer is more accurate definition of the extent of the known cancer, as well as identification of other areas of cancer in the affected breast or the opposite breast. For example, among 3% to 5% of women with a newly diagnosed breast cancer, MRI will identify previously undetected cancer in the opposite breast.
- It’s still unclear whether use of MRI to guide treatment decisions will reduce the risk of recurrence or improve survival.
- It’s important to remember that MRI can produce false-positive results. This means that areas that are suspicious for cancer on the basis of MRI will generally need to be biopsied to confirm the presence of cancer. Centers that perform breast MRI should also be able to perform MRI-guided biopsy or needle localization.
- Proper equipment, imaging technique, and provider training are important to achieving the best results from MRI.
Disadvantages of MRI
MRI also has some disadvantages including the need for the injection of a contrast agent, and false-positive enhancement of some benign tissues.
MRI is essentially contraindicated in some individuals because of physical constraints that prevent adequate patient positioning. These constraints include the following:
- Contraindication to gadolinium-based contrast media (eg, allergy, pregnancy)
- Patient's inability to lie prone
- Kyphosis or kyphoscoliosis
- Extremely large breasts
- Severe claustrophobia – although anxiolytic medications may help.
- Lehman CD, DeMartini W, Anderson BO, Edge SB. Indications for breast MRI in the patient with newly diagnosed breast cancer. Journal of the National Comprehensive Cancer Network. 2009;7:193-201.
- Bilimoria KY, Cambic A, Hansen MN, Bethke KP. Evaluating the impact of preoperative breast magnetic resonance imaging on the surgical management of newly diagnosed breast cancers. Archives of Surgery. 2007;142:441-447.
- Efficacy of MRI and mammography for breast-cancer screening in women with a familial or genetic predisposition. The New England Journal of Medicine. 2004; 351:427-437
- Warner E, Hill K, Causer P et al. Prospective study of breast cancer incidence in women with a BRCA1 or BRCA2 mutation under surveillance with and without magnetic resonance imaging. Journal of Clinical Oncology. Early online publication March 28, 2011.
- Horst K, et al. MRI Helps Doctors Select Best Treatment for Early Breast Cancers. Presented October 17, 2005. Proceedings from the 47th annual meeting of the American Society for Therapeutic Radiation Oncology (ASTRO). October, 2005. Denver, Colorado.
- Blair S, McElroy M, Middleton MS et al. The Efficacy of Breast MRI in Predicting Breast Conservation Therapy. Journal of Surgical Oncology. 2006;94:220-225.
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