Selective Use of Sentinel Lymph Node Surgery in Patients Undergoing Prophylactic Mastectomy Using Intraoperative Pathology

Background: Routine sentinel lymph node (SLN) surgery during prophylactic mastectomy (PM) is unnecessary, because most PMs do not contain cancer. Our institution utilizes intraoperative pathology to guide the surgical decision for resection of SLNs in PM. The purpose of this study was to review the effectiveness of this approach. Methods: We identified all women aged ≥18 years who underwent bilateral PM (BPM) or contralateral PM (CPM) at our institution from January 2008 to July 2016. We evaluated the frequency of SLN resection and rate of occult breast cancer (DCIS or invasive disease) in the PM. We used the following definitions: over-treatment—SLN surgery in patients without cancer; under-treatment—no SLN surgery in patients with cancer; appropriate treatment—no SLN in patients without cancer or SLN surgery in patients with cancer. Results: PM was performed on 1900 breasts: 1410 (74.2%) CPMs and 490 (25.8%) BPMs. Cancer was identified in 58 (3.0%) cases (32 invasive disease and 26 DCIS) and concurrent SLN surgery was performed in 44 (75.9%) of those cases. Overall, SLN surgery guided by intraoperative pathology resulted in appropriate treatment of 1787 (94.1%) cases: 1319 (93.5%) CPMs and 468 (95.5%) BPMs, by avoiding SLN in 1743/1842 cases without cancer (94.6%), and performing SLN surgery in 44/58 cases with cancer (75.9%). Conclusions: Use of intraoperative pathology to direct SLN surgery in patients undergoing PM minimizes over-treatment from routine SLN in PM and minimizes under-treatment from avoiding SLN in PM, demonstrating the value of intraoperative pathology in this era of focus on appropriateness of care.