Comparison of localization methods for non-palpable breast tumours: radioactive Iodine 125 titan seeds vs guide wire

Introduction A new method for localization of non-palpable breast cancer with Iodine 125 titan seeds during surgery was introduced at Bröstcentrum, Malmö, during 2022. The aim of the current analysis was to compare this method to the previous approach with wire-guided localization. The primary endpoint was positive margins, i.e. non-radical surgery. Method The current study included 50 consecutive patients with a non-palpable breast tumour visible on ultrasound diagnosed in 2023. Their tumours were marked with a 2 Mbq radioactive seed. This group was compared to a cohort of 432 consecutive patients with standard wire-guided localization diagnosed between 2015 and 2016. The primary outcome was positive margins, and the secondary outcome was determinants for positive margins. All information was obtained using digitalised clinical notes including data on anthropometric factors, tumour characteristics and the surgical procedure. The comparison between patients used the Chi-square test. Result Positive margins were identified in 12% of patients in the group who underwent the Iodine 125 seed procedure, results were similar to the historical reference group (18%). No significant differences were seen between patients with positive vs. clear margins regarding determinants, e.g. age, BMI, breast size, tumour characteristics or specimen weight. Discussion The new method for localization of non-palpable breast cancer showed to be reliable. The proportion of patients with positive margins was similar to that seen in the reference group where guide wires had been used. Reference Ellbrant J et al, Validated prediction model for positive resection margins in breast-conserving surgery based exclusively on preoperative data. BJS, 2021.