Little Benefit in Adding Ultrasound to Screening Mammography

While supplemental ultrasound with mammograms is regularly used as a screening tool for women with an increased cancer risk due to high-density breasts, the addition of ultrasound did not significantly improve survival among breast cancer patients, a new study found.

“We found no significant screening benefit as measured by greater sensitivity, increased cancer detection rate, or decreased false-negative rate,” according to Janie M. Lee, MD, and colleagues at the University of Washington in Seattle in JAMA Internal Medicine.

Breast ultrasound screening did, however, more than double the recommendations for biopsies, the researchers found, with 52.0 per 1,000 screens in women in the supplemental ultrasound group versus 22.2 per 1,000 in women receiving mammograms alone. Yet, cancer death rates for those who received mammograms plus ultrasound were 5.4 per 1,000 screens compared to 5.5 per 1,000 with mammography alone.

The findings raise new questions about the balance of harms and benefits from supplemental imaging.

“Most other studies have found significant increases in incremental cancer detection rate with mammogram plus ultrasounds compared with mammography alone,” the authors noted in their discussion of the findings.

“Our study reflects ‘real world’ use of screening ultrasound outside of the clinical trial setting and it is one of the largest studies from the United States.”

Using data collected in two Breast Cancer Surveillance Consortium registries, mammography plus ultrasonography examinations were matched 1:5 to 30,062 mammography examinations in 15,176 women.

Researchers analyzed 6,081 mammography plus ultrasonography examinations in 3,386 women to compare to 113,293 women in the overall mammography alone group prior to 1:5 matching design.

Women who received mammograms plus ultrasounds were more likely to be younger than 50 years and were 38.4% more likely to have dense breasts than those who received mammograms alone. However, about a quarter (25.7%) of women receiving supplemental ultrasounds did not have dense breasts.

Among the study’s other findings:

• The short-interval follow-up rate significantly increased by 2.8% among those who received supplemental ultrasound versus mammograms
• Mammography plus ultrasonography screening was associated with 16.9% fewer end-of-day assessments for additional imaging and 7.7% lower overall recall rate for additional imaging or biopsy
• The ultrasound cohort had 14.8% more women with high BCSC 5-year risk scores (≥2.50%) and 53.6% had low or average risk (<1.67%)

“The study data shows that they’re still looking for the best way to use ultrasound as a screening tool and which particular subgroup of women would benefit most from ultrasound screening, ” said Bonnie Joe, MD, of the University of California, San Francisco, told MedPage Today.

“It would be useful to refine the criteria for further subgroup analysis, since the study design combined heterogeneously dense and extremely dense breasts together for analysis. There is a need to focus more on the 13.3% of women in the study with extremely dense breasts,” said Joe, who is not involved in the study.

“Overall, the study is surprising and makes people less inclined to use ultrasound as a screening tool,” said Joe.

“However, we have to be careful not to redefine breast screening in such a way that could potentially be confusing for women. We still want to encourage them to receive an ultrasound with their mammogram if they would benefit.”