An International Randomized Prospective Trial Comparing a Supine MRI-based Guidance System, The Breast Cancer LocatorTM, to Wire Localization for Breast-Conserving Surgery for Non-palpable Breast Cancer
In brief
MRI guidance yields 32% fewer positive margins, but misses superiority threshold
In 418 patients having breast-conserving surgery, the MRI-based Breast Cancer Locator group had positive margins in 14.4%, versus 21.1% with wire localization, and fewer patients needed re-excision. The system met the trial's noninferiority test, but the primary analysis did not establish superiority; a prespecified analysis by tumor type did find fewer positive margins, warranting further scrutiny.
- Journal
- Annals of surgical oncology (Q1)
- Published
- 22 October 2026
- Study design
- Randomized controlled trial
- Evidence level
- Level 1, High (CEBM 1b)
- Authors
- Jennifer S Gass, Sarah Pesek, Brian Czerniecki, Jessica Ryan, David Edmonson, Wey-Liang Leong, et al.
- PMID
- 42918953
- DOI
- 10.1245/s10434-026-20657-6
Why clinicians should know about it
- Picked for Breast and Endocrine Surgery (paper of the day, 24 October 2026): Randomized trial of MRI‑based guidance vs wire localization for BCS
- Picked for Radiology, Radiation Oncology, Nuclear Medicine, Medical Physics and Imaging (paper of the day, 24 October 2026): Randomized comparison of MRI-guided breast localization and wire localization
Abstract
BACKGROUND: Positive margins after breast-conserving surgery (BCS) require additional surgery, a negative patient experience that also adds costs to care. Pilot trials indicate the Breast Cancer LocatorTM (BCL), a novel supine magnetic resonance imaging-based guidance system, helps surgeons resect cancers with a low positive margin rate (PMR). Our objective was to evaluate BCL noninferiority and superiority compared with wire localization (WL) in reducing the PMR with BCS. METHODS: Patients with nonpalpable, magnetic resonance imaging-visualized invasive breast cancer or ductal carcinoma in situ undergoing BCS were prospectively randomized to either BCL or WL. RESULTS: In total, 418 randomized patients underwent surgery. The PMR was 14.4% (30/209) in the BCL group and 21.1% (44/209) in the WL group, a relative decrease of 32%. In primary analysis, the treatment difference was -7.1% (95.4% confidence interval [CI] -14.3 to 0.1). Noninferiority was demonstrated (p = 0.011). The one-sided p-value for superiority (p = 0.025) slightly exceeded the prespecified significance level of 0.023. In prespecified analysis stratified by final tumor type, the PMR was significantly lower in the BCL group (p = 0.019). Fewer BCL patients underwent re-excision: 12.9% versus 19.6%, a relative decrease of 34%. The PMR for all tumor types was lower in the BCL group, with a > 60% relative reduction in PMR in patients with ductal carcinoma in situ (20.6% vs. 53.3% [95% CI -52.1 to -9.1]) and invasive lobular carcinoma (9.1% vs. 25.6% [95% CI -32.9 to -0.2]). Adverse event rates were similar. CONCLUSIONS: BCL was noninferior to WL and superior in analysis stratified by final tumor type. Clinically meaningful relative reductions in PMR and re-excision rates were observed.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.