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Adding Ultrasound and MRI to Mammography Finds More Cancer in High-Risk Patients

How should they be added to screening regimen for women with increased risk?

A study of approximately 2,800 women at high risk of breast cancer found that adding ultrasound or MRI to their annual mammography found more incident breast cancers than MRI alone, according to a study published this month in The Journal of the American Medical Association.

“Annual ultrasound screening may detect small, node-negative breast cancers that are not seen on mammography,” the authors wrote. “Magnetic resonance imaging may reveal additional breast cancers missed by both mammography and ultrasound screening.”

The study, led by Wendie A. Berg, MD, PhD, included 2,809 women at 21 sites with an increased cancer risk and dense breasts. The women (mean age of 55) consented to three annual, independent screens with mammography and ultrasound in randomized order. After three rounds of both screenings, 612 of 703 women chose to undergo an MRI and had complete data.

A total of 2,662 women underwent 7,473 mammogram and ultrasound screenings, 110 of whom had 111 breast cancer events. Fifty-nine cancers (53%) were detected by mammography, including 33 (30%) that were detected by mammography only; 32 (29%) by ultrasound only; and nine (8%) by MRI only after both mammography and ultrasound screens failed to detect cancer. Eleven cancers (10%) were not detected by any imaging screen. A total of 16 of 612 women (2.6%) in the MRI substudy were diagnosed with breast cancer.

Among 4,814 incidence screens in the second and third years combined, 75 women were diagnosed with cancer. The researchers found that supplemental ultrasound increased cancer detection with each annual screen beyond that of mammography, adding detection of 5.3 cancers per 1,000 women in the first year; 3.7 women per 1,000 per year in each of the second and third years; and averaging 4.3 per 1,000 for each of the three rounds of annual screening. The addition of MRI screening further increased cancer detection, with a supplemental cancer detection yield of 14.7 per 1,000 women. 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.

“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 authors wrote.

— Source: American Medical Association