Abstract
Introduction: Tc-99m tilmanocept (TcTM) received recent FDA-approval for lymphatic mapping. However, no prior studies have evaluated the use of TcTM as a single agent in sentinel lymph node (SLN) biopsy in breast cancer. Methods: We executed this retrospective, pilot study to assess the ability of TcTM to identify sentinel nodes as a single agent in clinically node-negative breast cancer patients. Patients received a single, intradermal injection overlying the tumor of either 0.5 mCi TcTM the day-of surgery or 2.0 mCi TcTM the day-prior to surgery by a radiologist. Immediate, three-view lymphoscintigraphy was performed. Intraoperatively, SLNs were identified with the use of a portable gamma probe. A node was classified as “hot” if counts per second of the node > 3 times that of background counts. Descriptive statistics are reported. Results: 19 patients underwent SLN biopsy with single-agent TcTM. Immediate lymphoscintigraphy identified ≥ 1 sentinel node in 13/17 (76.5%) patients. Intraoperatively, ≥ 1 (mean 1.7 ± 0.8, range 1-3) “hot” node was identified in all (100%) patients. Three (15.8%) patients had one disease-positive SLN. Conclusion: In this small retrospective pilot study, TcTM performed well as a single agent for intraoperative sentinel node identification in breast cancer. A larger, randomized clinical trial is warranted to compare Tc-99m tilmanocept as a single agent to other radiopharmaceuticals for sentinel node identification in breast cancer.