Does Screening Automated Breast Ultrasound (ABUS) Reduce False Alarms Compared to Handheld US (HHUS) in Women with Dense Breasts?
Background
Supplemental US is commonly recommended for women with dense breasts who cannot undergo breast MRI or who need additional screening beyond mammography. Although annual HHUS improves cancer detection by an average of 2-3 cancers per 1000 women screened, it is highly operator dependent and frequently results in BI-RADS 3 assessments that require short-interval follow-up.
Automated breast ultrasound (ABUS) was developed to provide standardized whole-breast imaging with improved reproducibility. Until recently, however, relatively few large-scale U.S. analyses have compared the performance of ABUS with HHUS in routine clinical practice.
Recent Study
In a recent study using Breast Cancer Surveillance Consortium (BCSC) data, investigators evaluated 25,328 supplemental screening US examinations performed in 21,446 women with dense breasts between 2014 and 2020.¹ The examinations were interpreted by 98 radiologists across 27 U.S. imaging facilities. Researchers compared the performance of ABUS and HHUS after adjusting for patient breast cancer risk and facility characteristics.
Key Findings
- ABUS was associated with a significantly lower abnormal interpretation and false-positive rates compared to HHUS.²
- The rate of short-interval follow-up recommendations was substantially lower for ABUS than for HHUS.³
- Cancer detection rates (CDR) were comparable between the two modalities⁴.
- There were no significant differences in biopsy recommendation rates or actual biopsies performed between ABUS and HHUS⁵.
These findings suggest that ABUS is an effective alternative to HHUS for supplemental screening in women with dense breasts. With ABUS, it is easier to recognize multiplicity and bilaterality of benign-appearing masses and to assess such cases as BI-RADS 2, benign, rather than BI-RADS 3 with unnecessary six-month follow-up examinations, patient anxiety, and associated healthcare costs. Importantly, these improvements were achieved without compromising cancer detection, as ABUS detected cancers at rates comparable to HHUS while generating fewer false-positive screening assessments. By providing standardized, reproducible whole-breast imaging that is less dependent on operator technique, ABUS may improve the consistency and efficiency of supplemental screening programs for women with dense breasts.
Limitations
ABUS generates over 1000 images for review and interpretation time was not considered. Unlike HHUS, there is no Doppler or elastography with ABUS, sometimes necessitating recall for more complete characterization of findings. False-positive rates decrease with incidence screening and this study did not distinguish prevalence from incidence screens, with 70.5% of the examinations reported having no prior screening US. The BCSC registries may not fully represent all U.S. screening practices, and investigators could not determine whether HHUS examinations were performed by radiologists or technologists. Cancer outcomes were limited to 90-day follow-up, potentially underestimating cancers initially classified as BI-RADS 3. Incomplete one-year follow-up prevented formal estimates of sensitivity and specificity.
Detailed Results
¹ The study included 21,446 women with dense breasts who underwent 25,328 supplemental screening US examinations, including 4,218 ABUS and 21,110 HHUS examinations. Most examinations were performed in women with heterogeneously dense breasts (21,913; 87%), while 3,415 (13%) were performed in women with extremely dense breasts. The vast majority of women had tomosynthesis (22,383; 89% overall).
² The adjusted abnormal interpretation rate was 14.9% (95% CI, 13.8%–15.9%) for ABUS compared with 19.2% (95% CI, 18.7%–19.8%) for HHUS (P<.0001). ⁶ Adjusted false-positive initial assessment rates were 14.6% (95% CI, 13.6%–15.7%) for ABUS compared with 19.1% (95% CI, 18.5%–19.6%) for HHUS (P<.0001).
³ The adjusted short-interval follow-up recommendation rate was 3.0% (95% CI, 2.5%–3.5%) for ABUS versus 14.6% (95% CI, 14.1%–15.0%) for HHUS (P<.0001).
⁴ Adjusted cancer detection rates were statistically similar between ABUS and HHUS at 2.5 cancers per 1,000 examinations (95% CI, 1.0–4.0) versus 1.7 cancers per 1,000 examinations (95% CI, 1.1–2.2), respectively (P=.33).
⁵ Adjusted biopsy rates were similar for ABUS (2.7%; 95% CI, 2.2%–3.2%) and HHUS (2.6%; 95% CI, 2.4%–2.8%) (P=.75) and PPV3 of biopsies remained low at 9.5% (95% CI 3.8%-15.3%) for ABUS and 6.4% (95% CI 4.3%-8.5%) for HHUS (P=.33).