Comparison of supplemental breast cancer imaging techniques-interim results from the BRAID randomised controlled trial

Abstract

Background: It is not known which supplemental imaging technique is most beneficial for women with dense breasts attending breast screening. This study compares abbreviated MRI, automated whole breast ultrasound (ABUS), and contrast-enhanced mammography versus standard of care in women with dense breasts and a negative mammogram. We report on interim results from the first round of supplemental imaging.

Methods: In this UK randomised controlled trial, at ten breast screening sites, women (aged 50-70 years) were independently allocated by batches (day/mobile screening van) to either abbreviated MRI, ABUS, or contrast-enhanced mammography or standard of care (full-field digital mammography) varied by modality availability at each centre. Women were invited if their mammogram was negative and they had dense breasts. Primary outcome was detection rate, defined as the percentage of women with a positive result on supplemental imaging that resulted in histologically confirmed breast cancer. Analysis was by imaging received (intention to treat) using network meta-analysis, treating each site as a study in the meta-analysis, with two analyses carried out: one using only the three active intervention arms (primary analysis) that compared the three supplemental imaging techniques with respect to cancer detection, recall, and biopsy rates in addition to those resulting from full-field digital mammography alone; and one with the addition of the observational data from Cambridge on full-field digital mammography alone. This trial is closed for recruitment and is registered with ClinicalTrials.gov, NCT04097366.

Findings: From October 18, 2019, to March 30, 2024, 9361 eligible women were recruited and randomly assigned (2318 to abbreviated MRI, 2240 to ABUS, 2235 to contrast-enhanced mammography, and 2568 to standard of care). Of those, 6305 completed supplementary imaging (2130 in the abbreviated MRI, 2141 in the ABUS, and 2035 in the contrast-enhanced mammography) and were included in the outcome analysis. The cancer detection rate was 17·4 (95% CI 12·2-23·9, n=37) per 1000 examinations for abbreviated MRI, 4·2 (1·9-8·0, n=9) per 1000 examinations for ABUS, and 19·2 (13·7-26·1, n=39) per 1000 examinations for contrast-enhanced mammography, of which 15·0 (10·3-21·1, n=32) per 1000 women for abbreviated MRI, 4·2 (1·9-8·0, n=9) per 1000 examinations for ABUS, and 15·7 (10·8-22·1, n=32) per 1000 examinations for contrast-enhanced mammography were invasive cancers. The detection rates for abbreviated MRI were significantly higher than for ABUS (p=0·047) and non-significantly higher than for contrast-enhanced mammography (p=0·62). There was one case of extravasation in the abbreviated MRI arm (0·5 events per 1000 examinations), no adverse events in the ABUS arm, and 24 iodinated contrast reactions (17 minor [8·4 events per 1000 examinations], six moderate [2·9 events per 1000 examinations], and one severe [0·5 events per 1000 examinations]) and three extravasations (1·5 extravasations per 1000 examinations) in the contrast-enhanced mammography arm.

Interpretation: Abbreviated MRI and contrast-enhanced mammography detected three times as many invasive cancers compared with ABUS, with cancers being half the size. This study shows that supplemental imaging could lead to earlier detection of cancer in women with dense breasts but does not estimate the level of overdiagnosis.

Funding: Cancer Research UK, GE Healthcare, and Bayer Healthcare.