Breast Ultrasound Recs May Not Be Targeting the Right Women

While recommendations for supplementary whole-breast ultrasounds were targeted to women with heterogeneously or extremely dense breasts, only a small proportion were at high risk of mammography screening failure, according to an observational study.

Over 95% of more than 38,000 ultrasounds were among women with dense breasts compared with 41.8% of over 825,000 screening mammograms without supplemental screening (P<0.0001), reported Brian Sprague, PhD, of the University of Vermont Larner College of Medicine in Burlington, and co-authors.

High interval invasive breast cancer risk was prevalent in 23.7% of screening ultrasounds among women with dense breasts compared with 18.5% of screening mammograms without supplemental imaging (adjusted OR 1.35, 95% CI 1.30-1.39), while intermediate/high advanced cancer risk was prevalent in 32.0% versus 30.5%, respectively (adjusted OR 0.91, 95% CI 0.89-0.94), they noted in Cancer.

"What we found was that ultrasound screening is indeed heavily targeted to women with mammographically dense breasts," Sprague told MedPage Today. "But amongst this large group of women who have dense breasts, there wasn't much difference in terms of their other breast cancer risk factors."

"Our data indicate that the women who are most likely to benefit from supplemental ultrasound screening -- so those who have high breast cancer risk and have mammographically dense breasts -- are not necessarily the ones who are getting ultrasound screening right now," he said.

"It's kind of a wake-up call that doctors and women may want to reconsider how they're making decisions about ultrasound screening," he added.

Ultrasound screening following a standard mammogram can help detect cancers that might have been initially missed, the researchers noted. However, "this gain is accompanied by potential harms, including recall for additional imaging and benign breast biopsy among women who do not have breast cancer (false positives)."

Aside from breast density, certain breast cancer risk factors, such as family history of breast cancer or prior benign breast disease, "have been shown to be associated with likelihood of a mammography screening failure," they wrote.

Last month, the U.S. Preventive Services Task Force (USPSTF) announced that they were updating breast cancer screening guidelines to lower the screening age recommendations to 40 for some women, rather than 50 as it had been for years.

Nina Vincoff, MD, chief of breast imaging at Northwell Health in Long Island, New York, said the study's findings illuminate an opportunity to better educate both patients and physicians on the importance of breast cancer risk assessment.

"It's encouraging to see that women with dense breasts are getting extra screening with ultrasound. However, other women at risk may not be getting all the testing that they need," she told MedPage Today.

Vincoff echoed the need for a more specific screening guidance "so that all women can have the testing that is tailored to them and their specific risk factors."

For this study, Sprague and team analyzed data from 2014 to 2020 from the Chicago, San Francisco, and Vermont registries of the Breast Cancer Surveillance Consortium (BCSC). They included 38,166 screening ultrasounds and 825,360 screening mammograms without supplemental screening from 29,112 and 377,140 women, respectively.

Four categories of breast density were used, using standard Breast Imaging Reporting and Data System (BI‐RADS) descriptions: almost entirely fatty, scattered fibroglandular densities, heterogeneously dense, or extremely dense.

Among all ultrasounds, 75% were the woman's first, and 63% occurred within 9 months of a mammogram. Nearly 70% of ultrasound screenings occurred among women ages 40 to 59 compared with just 3% of women under 40 and 29% of women 60 and older. A quarter of ultrasound screenings were among Asian, Black, or Hispanic women compared with 73% among white women.

To assess different kinds of cancer risk, the researchers used the BCSC 5-year risk model to determine risk for invasive breast cancer and interval invasive breast cancer, and used the BCSC 6-year advanced breast cancer risk model to estimate advanced breast cancer risk. High interval invasive breast cancer risk was defined as heterogeneously dense breasts and BCSC 5-year breast cancer risk ≥2.5% or extremely dense breasts and BCSC 5-year breast cancer risk ≥1.67%. Intermediate/high advanced cancer risk was defined as BCSC 6-year advanced breast cancer risk ≥0.38%.

Sprague said that randomized trials on ultrasound screening could eventually lead to national guidelines that would help physicians determine which patients need additional ultrasound screening.

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