Breast MRI is widely used in the preoperative evaluation of breast cancer to assess the extent of local disease and assist in surgical planning. Studies have shown that breast MRI is more sensitive than traditional imaging methods like mammography and ultrasound in detecting additional disease, often altering surgical management. However, the impact of these additional findings on long-term outcomes, such as local recurrence rates, remains unclear, with most existing data being retrospective. Previously, a single prospective trial conducted in Brazil found no significant difference in local recurrence between patients who underwent preoperative MRI and those who did not, but this study predominantly included patients with hormone receptor (HR)-positive breast cancer, which is associated with lower local recurrence risks. The Alliance A011104/ACRIN 6694 trial aimed to address these gaps by focusing on patients with HR-negative breast cancer, a population at higher risk for local recurrence, to evaluate whether breast MRI could improve oncologic outcomes in this subgroup.

Participants with newly diagnosed breast cancer, clinical stage I-II (T1-T3N0 or T0-2N1), HR-negative, HER2-positive or -negative, who were eligible for breast-conserving surgery (BCS) were randomized into 2 groups: 1 receiving routine imaging without MRI, and the other undergoing preoperative breast MRI within 30 days of mammography. Patients were followed for a primary endpoint of local regional recurrence (LRR) over 5 years, with secondary endpoints including LRR in the BCS subset, distant recurrence-free survival, overall survival, and re-excision rates. The study also implemented a strict algorithm for managing MRI-detected disease to mitigate overtreatment.

The trial enrolled 319 patients (MRI arm: n=161; no MRI arm: n=158) with newly diagnosed breast cancer who were eligible for BCS. The results revealed no significant difference in 5-year LRR rates between the MRI and no-MRI groups, with 95.7% of patients in the no-MRI arm and 93.2% in the MRI arm free of local regional recurrence. Similarly, there were no differences in distant recurrence-free survival (94.3%) or overall survival (92.2%) between the 2 groups. Subgroup analyses also found no benefit of MRI based on tumor subtype (HER2-positive or triple-negative) or patient age. Surgical outcomes, including BCS rates, margin positivity, and re-excision rates, were comparable between the arms. Notably, the majority of patients received systemic therapy and radiation, which likely contributed to the excellent local control observed across the cohort.

This trial demonstrates that routine preoperative breast MRI does not improve oncologic outcomes in early-stage HR-negative breast cancer. The findings suggest that advances in mammographic imaging and widespread use of ultrasound may have reduced the utility of MRI for local staging. Additionally, the combination of systemic and radiation therapies may effectively address residual disease that MRI detects. As a result, clinicians may reconsider the routine use of breast MRI in surgical planning, reserving it for specific cases where its benefits are clearly defined. Further analyses, including re-excision rates, are ongoing to provide additional insights from this study.

Source: Bedrosian I, Ballman K, McCall L, et al. Effect of preoperative breast MRI staging on local regional recurrence (LRR) in early stage breast cancer: Alliance A011104/ACRIN 6694. Presented at: San Antonio Breast Cancer Symposium 2025. December 11, 2025; San Antonio, TX. Presentation GS2-07.