Adjunct Automated Breast Ultrasound in Mammographic Screening: A Systematic Review and Meta-Analysis

Mammographic sensitivity is reduced in women with dense breasts, leading to missed cancers and a higher burden of interval cancers. Automated breast ultrasound (ABUS) and ultrasound tomography (UST) have been introduced as supplemental breast imaging modalities, but primary studies are heterogeneous, and previous reviews have not focused on screening settings or on head-to-head comparisons with handheld ultrasound (HHUS). We systematically searched PubMed, Embase, Web of Science and the Cochrane Library for studies from 1 January 2000 to 31 May 2025 evaluating ABUS or UST as adjuncts to mammographic screening. Two reviewers independently selected studies and assessed risk of bias. When at least two clinically comparable studies were available, we pooled sensitivity and specificity using random-effects bivariate meta-analysis. Eighteen studies (just over 20,000 screening or recall episodes) met the inclusion criteria; 16 evaluated ABUS/ABVS and 2 UST. Adding ABUS to mammography increased sensitivity by 6-35 percentage points and improved cancer detection by 2.4-4.3 per 1000 women with dense breasts, with higher recall rates and modest reductions in specificity. When ABUS was compared directly with HHUS, pooled sensitivity was 0.90 and specificity 0.89, with HHUS showing slightly lower sensitivity and slightly higher specificity. Only two studies had an overall low risk of bias, and heterogeneity (particularly for specificity) was substantial. ABUS is a practical and scalable adjunct to mammography that increases cancer detection in women with dense breasts, with an expected trade-off of higher recall and modest specificity loss. Its comparative diagnostic accuracy appears broadly non-inferior to HHUS. However, the predominance of high-risk-of-bias studies and between-study heterogeneity means that high-quality population-based trials and standardised reporting are still required before widespread implementation in organised screening programmes.