16 Magseed Versus Wire Localisation: A Comparison

Background

The localization of impalpable breast lesions has historically been wire-guided. However, this is associated with such challenges as patient discomfort, wire migration, and restrictive scheduling. Magseed, which provides scheduling flexibility and improves patient comfort, has recently been adopted in our unit. Our study compares the efficacy of Magseed with the wire, with a particular focus on reexcision rates.

Methods

Data were collected retrospectively from 1 United Kingdom (UK) breast unit from consecutive cases over a 10-month period in 2021, from the start of Magseed adoption, comparing reexcision rates for Magseed-guided to wire-guided wide local excisions (WLE). Baseline data on body mass index (BMI), ethnicity, age, and previous breast procedures were recorded. The other outcomes were breast quadrant, localization technique, largest tumor size on all imaging modalities, histology size, core biopsy, and final histology. Locally, American Society of Clinical Oncology margin guidelines are followed: no ink on tumor for invasive disease, 2-mm clearance for ductal carcinoma in situ.

Results

We identified 62 patients (63 breasts) in the Magseed group and 50 patients (52 breasts) in the wire group. The median age in the Magseed group was 59 years (range, 28-89) and the median BMI was 28.23 (range, 19.10-59.40), vs median age of 61 years (range, 37-92) and median BMI 27.85 (range, 18.50-43.50) for the wire group.

The median size on imaging for the Magseed group was 17 mm (range, 0-54), vs 12.5 mm (range, 0-67) for the wire group. On final histology, the median size in Magseed cases was 21 mm (range, 0-82) vs 17 mm (range, 0-68.8) for wire cases. There was a significant difference between largest size on imaging and final histology size in both groups (Magseed, P = .034; wire, P = .028). The median histology size in reexcision cases in the Magseed group was 40 mm (range, 17-82) vs 26.75 mm (range, 17-58) in the wire group.

The overall reexcision rate in the Magseed group was 14.5% (9/63), compared with 15.4% (8/52) in the wire group.

Conclusions

Our data show similar reexcision rates when comparing Magseed with the traditional wire-guided localization. The significant difference between size on imaging and histology has implications for reexcision rates and therefore additional work is required to improve the preoperative estimation of cancer size and address this discrepancy. A reduction in reexcision rates may also be improved over time as operators move up the learning curve and become more experienced with Magseed. Our data reflect “snapshot” early results, and we therefore aim to report further with a larger cohort in future analysis.

Author Affiliations:

Jessie Lenton, Emma Stewart-Parker, Nga Nguyen,1 Georgios Boustsikos, Nadine Betambeau, Dibyesh Banerjee, Anup Sharma, Sarah Tang

St. George’s University Hospitals NHS Foundation Trust, London, UK