According to a recent article published in The New England Journal of Medicine, magnetic resonance imaging (MRI) is more sensitive than mammography in the detection of early breast cancer in women at a high risk of developing the disease.
Breast cancer is diagnosed in approximately 250,000 women annually in the United States. A small portion of these patients have genetic mutations that put them at a higher than normal risk for the development of breast cancer. These patients often undergo regular screening in order to detect the cancer early, when it is most treatable. Researchers continue to evaluate which screening method detects the most cases of breast cancer while providing accurate readings. Screening methods that have been evaluated include a physical examination, mammography, ultrasound, MRI, CT scans or PET scans. Results from previous trials have indicated that MRI is more accurate than mammography in the detection of breast cancer in women undergoing surveillance for breast cancer.
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. Patients who are at a high risk of developing breast cancer may wish to speak with their physician about the risks and benefits of screening with mammography or MRI, or the participation in a clinical trial evaluating other screening measures. Two sources of information regarding ongoing clinical trials include the National Cancer Institute (cancer.gov) and www.cancerconsultants.com.
Reference: 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