Women with dense breast tissue face a higher risk of late-stage breast cancer diagnosis due to the limited sensitivity of standard mammography. In response, supplemental imaging techniques have been developed to improve cancer detection in this population. The Breast screening—Risk Adapted Imaging for Density (BRAID) trial, a UK-based randomised controlled study, evaluated the performance of three such modalities—abbreviated MRI, automated whole breast ultrasound (ABUS) and contrast-enhanced mammography—in women aged 50–70 with dense breasts and negative mammograms. This interim analysis of the first round of imaging offers critical evidence on detection efficacy, recall rates and safety, guiding future screening strategies for this high-risk group.
Comparative Performance of Supplemental Imaging Techniques
The BRAID trial involved 9361 eligible women across ten centres, randomised into four groups: abbreviated MRI (2130 participants imaged), ABUS (2141), contrast-enhanced mammography (2035) and a control group receiving standard mammography. The primary metric was the cancer detection rate per 1000 examinations. Abbreviated MRI identified 17.4 cancers, contrast-enhanced mammography 19.2 and ABUS 4.2. Both contrast-enhanced techniques significantly outperformed ABUS, detecting smaller and earlier-stage invasive tumours. The median tumour size for abbreviated MRI and contrast-enhanced mammography was approximately 10–11 mm, whereas ABUS detected larger tumours averaging 22 mm. Moreover, ductal carcinoma in situ (DCIS) was observed only in the contrast-enhanced groups, reinforcing the superior sensitivity of contrast-based methods.
Must Read: Non-Detected Cancers in One-View Breast Screening
Further analysis showed that abbreviated MRI and contrast-enhanced mammography detected three times as many invasive cancers as ABUS, with the majority of cancers being lymph-node-negative, suggesting early detection. Despite a similar detection rate between the two contrast-enhanced methods, abbreviated MRI showed a higher rate of HER2-enriched tumours. The data support the utility of abbreviated MRI as a less time-intensive yet highly effective alternative to full-protocol MRI, achieving comparable detection rates.
Safety Profiles and Recall Rates
Recall and biopsy rates are essential secondary measures in assessing the burden and efficiency of screening modalities. In the BRAID trial, abbreviated MRI and contrast-enhanced mammography both had recall rates of 9.7%, while ABUS had a significantly lower rate of 4.0%. Biopsy rates mirrored this trend: 4.9% for abbreviated MRI, 4.4% for contrast-enhanced mammography and 1.5% for ABUS. These findings indicate that although ABUS involves fewer follow-up procedures, it also yields considerably lower cancer detection.
In terms of adverse events, ABUS had none, making it the safest modality in procedural terms. Abbreviated MRI reported one case of extravasation, whereas contrast-enhanced mammography was associated with a higher incidence of contrast reactions—24 events, including one severe case and three additional extravasations. Although the safety profile of ABUS is favourable, the comparatively low detection rate challenges its effectiveness as a standalone supplemental screening tool.
The higher recall and biopsy rates for contrast-enhanced techniques are consistent with other large studies, yet they raise concerns about potential overdiagnosis and patient anxiety. Nonetheless, these modalities fall within the NHS Breast Screening Programme standards and offer high diagnostic value by identifying smaller and early-stage cancers.
Implementation and Implications for Screening Policy
The BRAID trial represents a pragmatic approach by allowing imaging modalities to be assigned based on equipment availability at participating centres. It confirms that contrast-enhanced imaging can be effectively integrated into a population-based screening programme. The abbreviated MRI protocol used was shorter and more feasible than traditional MRI, showing promise for wider adoption without compromising diagnostic yield.
Importantly, the trial also utilised the CanRisk tool to estimate each participant’s breast cancer risk, although this data did not influence imaging allocation. Most participants were at average risk, suggesting the findings are relevant for general screening populations. Despite limitations in directly comparing outcomes with standard mammography (only one site provided such data), network meta-analysis affirmed the superior performance of the supplemental techniques.
Longer-term outcomes such as breast cancer mortality reduction or overdiagnosis rates remain outside the scope of this interim analysis. However, the study establishes a foundation for modelling the cost-effectiveness and clinical impact of various imaging strategies. Future rounds of imaging and ongoing follow-up will help clarify these effects and guide evidence-based policy updates.
The BRAID trial interim results demonstrate that abbreviated MRI and contrast-enhanced mammography significantly improve cancer detection in women with dense breasts compared with ABUS and standard mammography. While ABUS offers a lower risk of procedural complications and fewer recalls, its limited sensitivity and higher tumour sizes question its utility as a primary supplemental imaging option. In contrast, the contrast-enhanced modalities, particularly abbreviated MRI, present a compelling balance of efficacy and feasibility. In the future, this evidence will be instrumental in shaping policy and practice towards more personalised, effective cancer detection.
Source: The Lancet
Image Credit: iStock
