Wire guided localization is the gold standard technique for pre-operative localization of non-palpable breast cancers in patients undergoing wide local excision (WLE). It has logistical challenges as it needs to be performed on the day of surgery, requiring coordination of Breast, Radiology and Theatre teams. Reported complications include wire displacement, intra-operative difficulty localizing the tip, pneumothorax, and cardiac injuries. Magseed is an alternative localization technique using a magnetic seed, which can be placed up to 30 days pre-operatively. This is localized intraoperatively with a ‘Sentimag probe’. The iBRA-NET Localisation Study performed in UK demonstrated magseed localization as an effective technique in terms of patient convenience and satisfaction, accurate localisation and avoiding unnecessary scheduling delays/cancellations. Our breast unit changed from using wires to predominantly Magseed localisations in early 2020.
Data was retrospectively collected for all patients undergoing wire or Magseed localised WLE for non-palpable invasive breast cancer or ductal carcinoma-in-situ from 01/10/2019 to 01/10/2020. Accuracy was determined by the presence of cancer and wire/Magseed in the specimen or cavity shave, presence of clear margins, and need for re-excision. Complications within 30 days of surgery were also recorded. Statistical analysis was performed using IBM SPSS statistics version 24 (Univariate analysis). P values under 0.05 were considered significant.
Magnetic seed (n=43) Wire (n=49) p-value p-value in national audit Accurate localization 42 (97.7%) 48 (97.9%) 0.730 0.048* Re-operation rate 8 (18.6%) 13 (26.5%) 0.458 0.574 Positive/Close margins 9 (20.9%) 9 (18.4%) 0.797 0.342 Specimen weight 34g (7.70-378.3g) 29g (5.5-201.4g) 0.362 0.362 Minor wound infection 3 2 0.147 0.170 Major wound infection (needing IV antibiotics) 1 0 0.352 0.527 Unexpected re-admission to hospital within 30 days 1 0 0.721 0.676 Peri-operative problem Magseed/wire dislodged from lesion 1 0 0.467 0.039* Index lesion/clip not visible on specimen X-ray 3 1 0.261 0.406 Type of surgery Wide local excision 37 48 0.032* 0.002* Therapeutic mammoplasty 5 1 Other (LICAP) 1 0
Magseed can be introduced safely into the DGH setting, with non-inferior results compared to wire localisations. The technique has advantages for both patients and scheduling teams. Our findings support those of the National Localization Audit.
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