Magnetic Seeds: An Alternative to Wire Localization for Nonpalpable Breast Lesions

Magnetic seeds have emerged as an alternative to wires for localization of nonpalpable breast lesions. The purpose of this study was to evaluate the utility of magnetic seeds compared to wires for preoperative localization.

A retrospective cohort analysis of magnetic seed localization (MSL) and wire localization (WL) excisional biopsies and lumpectomies performed at a single institution was conducted. Indication, age, BMI, number of markers, procedure type, operative time, and postoperative opioid administration were reviewed. Impact of localization method on operative time, specimen volume, postoperative opioid administration, and re-excision rate were assessed.

A total of 608 MSL procedures in 601 patients were compared to 628 WL procedures in 620 patients. MSL excisional biopsies were significantly longer (37.0 minutes) than WL excisional biopsies (31.9 minutes, P< .001), but in lumpectomies without axillary surgery, MSL procedures (42.3 minutes) were significantly shorter than WL procedures (46.9 minutes, P = .017). Significantly less tissue was excised during MSL lumpectomies (68.5 cm³) and excisional biopsies (32.3 cm³) than WL lumpectomies (78.1 cm³, P = .039) and excisional biopsies (38.7 cm³, P = .018). Postoperative opioid administration was similar for MSL and WL procedures (P = .076). Re-excision rates for MSL lumpectomies were significantly higher for ductal carcinoma in situ (35.3% MSL vs. 18.5% WL, P = .013), but were similar for invasive carcinoma (14.4% MSL vs. 17.7% WL, P = .290). Logistic regression analysis showed no association between localization method and re-excision (OR 1.007, 95% CI 0.681-1.488; P = .973).

MSL is a feasible alternative to WL for excision of nonpalpable breast lesions with regard to surgical outcomes.