Comparison of margin status and lesional size between radioactive seed localized vs conventional wire localized breast lumpectomy specimens

Despite the known benefits of the use of radioactive seed localization (RSL), few studies have looked at the resultant pathologic marginal status of these lumpectomy specimens, especially in regard to different definitions of close/positive margins. We compared the marginal status of lumpectomy specimens removed by either RSL or conventional wire localization (CWL) techniques. A total of 106 lumpectomy specimens including 62 by CWL and 44 by RSL for invasive ductal and lobular carcinomas were compared. Data on gross and microscopic surgical margin status, tumor type and grade, and demographic information were retrospectively collected. There was no difference between the techniques in terms of tumor characteristics including size, histologic grade, lymph node positivity, or age. Although the distributions are very similar between CWL and RSL specimens for final marginal assessments (P = .69), there is a (modest) statistically significant difference in the distribution for margin classifications based on gross assessments (P = .040), specifically more RSL specimens exhibiting tumor within 1 mm of the closest margin. Concordance between gross and microscopic lesion measurements is highest for invasive ductal carcinoma grade 3 for both CWL and RSL lumpectomies (78.6% and 80.0%). This study shows that there were no significant marginal status differences between RSL and CWL lumpectomy specimens with invasive carcinoma. Rather, what was relevant is whether the entire specimen could be classified as having negative/close margins. Significant workflow challenges in surgical pathology laboratories are expected with the adoption of the RSL process.