Breast conserving surgery for extensive DCIS using multiple radioactive seeds

Breast conserving surgery (BCS) can be challenging for large regions of ductal carcinoma in situ (DCIS), resulting in high rates of positive resection margins. Radioactive seed localization (RSL) using multiple radioactive iodine (125I) seeds can be used to bracket extensive DCIS (eDCIS). The goal of this study was to retrospectively compare the use of a single or multiple 125I seeds in RSL to enable BCS in patients with eDCIS. All patients with eDCIS (area of ≥3.0 cm) who underwent either single or multiple-seed RSL between January 2008 and December 2016 were included. Patient, tumor and surgery characteristics were compared between both groups. Primary outcome measures were positive resection margin and re-operation rates. Respectively 48 and 58 patients with eDCIS underwent single- and multiple-seed RSL and subsequent BCS. The rate of positive resection margin (focal and more than focal) with single-seed RSL was 47.9%, compared to 29.3% with multiple-seed RSL (p = 0.06). The re-operation rate was 39.6% with single-seed RSL and 20.7% in the multiple-seed RSL group (p = 0.05). Multiple-seed RSL enables bracketing of large areas of DCIS, with the potential to decrease the high rate of positive resection margins in this patient group.