Abstract P3-01-16: How hot is enough for accurate sentinel lymph node axillary staging in breast cancer?

Abstract

Abstract Purpose: Sentinel lymph node (SLN) biopsy is a well-established procedure for staging of the axilla in early-stage breast cancer and has replaced axillary lymph node dissection as the standard of care in patients with clinically lymph node–negative axilla. No consensus exists about the number of sentinel lymph nodes (SLNs) that should be removed based on radioactivity counts in breast cancer, although the “10% rule” is often used. In order to determine the frequency with which the hottest SLN 'fails' to be pathologically positive, and to determine which criteria best define the radioactive lymph node to be removed, we reviewed and analyzed our cases in which more than one SLN was detected and where there was also at least one pathologically positive node. Methods: We retrospectively studied 1062 breast cancer patients who underwent lymphoscintigraphy by injection of radioactive colloid and SLN biopsy between 2006 and 2015, with intraoperative determination of radioactive counts of nodes by a gamma probe. Results: A total of 247 patients (23.3%) had more than 1 SLN removed (mean 2.29); 53 patients (21.5%) had nodal metastases. Of the node-positive patients, the hottest SLN was positive in 90.6% (48 of 53). The lowest radioactive count of a positive SLN was 32% of that of the hottest node. Conclusions: In our study, most positive SLNs had the highest radioactivity and the hottest lymph node was not the pathologically positive node only in 9.4 %. Our institutional experience indicates that to obtain an acceptable false-negative rate, nodes should be removed until the 10% rule is met. Citation Format: Lee MH, Kang SH, Cho J. How hot is enough for accurate sentinel lymph node axillary staging in breast cancer? [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-01-16.