Legislative efforts to require information about breast density on mammography results provided to patients have raised awareness about the varying effectiveness of mammography. However, up until recently, there has been little data on what, if anything, women with dense breast tissue should do to improve their odds of early detection of breast cancer.
A study in the latest issue of the Journal of the American Medical Association (JAMA) partially answers this question. It shows that additional breast cancer screening with ultrasound and MRI can indeed catch a percentage of cancers missed on mammograms, but the researchers stopped short of recommending MRI screening.
"Despite its higher sensitivity, the addition of screening MRI rather than ultrasound to mammography in broader populations of women at intermediate risk with dense breasts may not be appropriate, particularly when the current high false-positive rates, cost, and reduced tolerability of MRI are considered," the study authors wrote in JAMA.
Still, because of the size of the patient population involved — the study included 2,809 women at 21 sites — and the prestige of having survived the JAMA peer review process, the results may be quite helpful to diagnostic imaging providers.
All the women in the study had increased cancer risk and dense breasts. They agreed to three yearly independent screens with mammography and ultrasound in randomized order. Median age at enrollment was 55 years. A little more than half of the women had a personal history of breast cancer. After three rounds of both screenings, 703 women chose to undergo an MRI.
Not all the women completed the study. At the end of the research. a total of 2,662 women had undergone 7,473 mammogram and ultrasound screenings. Among these women, 110 had 111 breast cancer events.
What will interest diagnostic imaging providers is that 59 of the 111 cancers detected (53 percent) were spotted by mammography, including 33 (30 percent) that were detected by mammography only. However, 32 cancers (29 percent) were only detected by ultrasound and 9 cancers (8 percent) were only detected by MRI after both mammography and ultrasound had missed finding the cancers. Eleven cancers (10 percent) were not detected by any imaging test.
Extrapolating the results into statistics, the researchers found that the number of screens needed to detect one cancer was 127 for mammography; 234 for supplemental ultrasound, and 68 for supplemental MRI after negative mammography plus ultrasound screening results.
The citation for referral sources is JAMA. 2012;307:1394-1404. Click here to go directly to the study abstract.