Contrast-enhanced mammography versus conventional imaging in women recalled from breast cancer screening (RACER trial): a multicentre, open-label, randomised controlled clinical trial

Background Women recalled from breast cancer screening receive post-screening work-up in the hospital with conventional breast imaging. The RACER trial aimed to study whether contrast-enhanced mammography (CEM) as primary imaging instead of conventional imaging resulted in more accurate and efficient diagnostic work-up in recalled women. Methods In this randomised, controlled trial (registered under NL6413/NTR6589) participants were allocated using deterministic minimisation to CEM or conventional imaging as a primary work-up tool in two general and two academic hospitals. Predefined patients 'factors were reason for recall, BI-RADS score, and study centre. Primary outcomes were sensitivity and specifi city. Secondary outcomes were the proportion of women needing supplemental examinations, and number of days until diagnosis. Findings Between April, 2018, and September, 2021, 529 patients recalled from the Dutch screening program were randomised, 265 to conventional imaging and 264 to CEM. Three patients in the control arm had to be excluded from analysis due to a protocol breach. After the entire work-up, sensitivity was 98.0% (95% CI; 92.2 - 99.7%) in the intervention arm and 97.7% (91.8 - 99.6%) in the control arm (p = 1.0), and speci fi city was 75.6% (72.5 - 76.6%) and 75.4% (72.5 - 76.4%, p = 1.0), respectively. Based on only primary full- field digital mammography/digital breast tomosynthesis or CEM, final diagnosis was reached in 27.7% (73/264) in the intervention arm and 1.1% (3/262) in the control arm. The frequency of supplemental imaging was signi fi cantly higher in the control arm (p < 0.0001). Median time needed to reach fi nal diagnosis was comparable: 1 day (control arm: IQR 0 - 4; intervention arm: IQR 0 - 3). Thirteen malignant occult lesions were detected using CEM, versus three using conventional imaging. No serious adverse events occurred. Interpretation Diagnostic accuracy of CEM in the work-up of recalled women is comparable with conventional imaging. However, work-up with CEM as primary imaging is a more efficient pathway. Copyright (c) 2024 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).