Progressnotes - October/November 2012
- About MUSC Health
An article published in the April 4, 2012 issue of the Journal of the American Medical Association provides evidence that supplementing annual mammography with ultrasound or magnetic resonance imaging (MRI) leads to significantly higher detection rates of early, node-negative, invasive breast cancers than mammography alone in women with dense breast tissue and at least one other risk factor for breast cancer.1
The article, coauthored by Etta D. Pisano, M.D., Professor of Radiology and Dean of the College of Medicine at MUSC, reported the results of an American College of Radiology Imaging Network (ACRIN) 21-site trial conducted from April 2004 through February 2006 that enrolled 2662 women. Participants underwent three rounds of annual mammography and ultrasound, and a subset of women (n=612) in whom no breast cancer was detected during these three rounds of screening consented to supplemental MRI.
A single ultrasound screening has previously been shown to increase the detection rate of early invasive breast cancers by 3.5 and 4.2 to 4.4 per 1,000 screenings in single-center and multicenter trials, respectively. However, this study is the first to demonstrate continuing improvement in detection rates with repeated ultrasound screenings (5.3 cancers per 1,000 screenings per year in the first year and 3.7 cancers per 1,000 screenings per year in the second and third years, for an overall average of 4.3 cancers per 1,000 screenings per year).
Although this study confirms previous reports that MRI detects more early invasive breast cancers (an additional 14.7 cancers per 1,000 screens in this study) than combined mammography and ultrasound, its authors also note that MRI is expensive and may not be well tolerated by all patients. For women with an intermediate risk of breast cancer and dense breast tissue, especially those with a personal history of breast cancer, or high-risk patients who cannot tolerate MRI, combination mammography and ultrasound could represent a valuable and cost- effective screening mechanism for the detection of early invasive breast cancers.
Ultrasound and MRI are not substitutes for annual mammography but instead supplement its findings. It is important for every woman to speak with her physician about which screening process is most appropriate given her own medical history and risk profile.
Screening with either ultrasound or MRI is associated with a higher rate of false-positives, but that rate decreases after the first year with regular annual screening and is lower in women with a personal history of breast cancer. Limitations to the use of ultrasound for supplemental screening of intermediate-risk women with dense breast tissue are its low reimbursement rate by Medicare (not enough to cover a physician- conducted screening) and the shortage of trained breast ultrasound technologists.
1 Berg WA, et al. Detection of breast cancer with addition of annual screening ultrasound or a single screening MRI to mammography in women with elevated breast cancer risk. JAMA. 2012; 307:1394-1404.