Use of lymphoscintigraphy with Tc-99m tilmanocept does not affect the number of nodes removed during sentinel node biopsy in breast cancer

Objectives The utility of lymphoscintigraphy for sentinel lymph node (SLN) localization after radiopharmaceutical injection in clinically-node negative breast cancer has been questioned. No prior studies have examined the use of lymphoscintigraphy on the number of SLNs removed with Tc-99m tilmanocept (TcTM). The object of this study was to determine if there is a difference in the number of nodes removed during SLN biopsy in patients who have no lymphoscintigraphy imaging/no node on imaging versus patients with an identified node(s) on lymphoscintigraphy in clinically node-negative breast cancer patients.

Methods This is a single-institution, retrospective review on use of TcTM in SLN biopsy in clinically node-negative breast cancer patients. At our institution, three scenarios emerge: no lymphoscintigraphy image obtained, lymphoscintigraphy imaging obtained with no node localization and lymphoscintigraphy imaging obtained with 蠅 1 identified node. Patients were stratified into no imaging obtained/no node on imaging (NI) and node-identified on lymphoscintigraphy imaging (NP). Patients with prior SLN biopsy/axillary node dissection were excluded. Patients received an intradermal 0.5mCi of TcTM injection on day of surgery or 2.0mCi injection on day before surgery. Use of vital blue dye (VBD) injection (2-3mL) at time of surgery was up to the discretion of the operating surgeon. Nodes that were "hot", "blue" or palpably suspicious were considered SLNs. Student’s t-test was used to compare number of SLNs removed between groups. A zero-truncated negative binomial model was fitted to assess node-visualization on lymphoscintigraphy and other covariates on total number of SLNs removed. A p-value <0.05 was used for statistical significance.

Results Up until Dec 2015, 622 patients underwent SLN biopsy with TcTM +/- VBD. Eighty-six (13.8%) patients had no lymphoscintigraphy performed/no node identified on lymphoscintigraphy. There was 100% intraoperative SLN identification in the study population. TcTM and VBD were both used in 611 (98.2%) patients and 104 (16.7%) patients had 蠅1 positive node. The mean number of removed SLNs was 2.96. The mean number of nodes removed in the NP-group was 3.0 (SD 1.8) versus 2.7 (SD 1.9) in the NI-group, p-value= 0.21. On multivariate analysis, patient age, surgeon, presence of positive nodes and use of frozen section significantly affected the number of removed SLNs. The presence of a node identified on lymphoscintigraphy did not significantly affect the number of removed SLNs. No statistically significant interactions were detected among the covariates. See Table for the multivariate model.

Conclusions When using TcTM in SLN biopsy in clinically node-negative breast cancer patients, the identification of a node on lymphoscintigraphy did not significantly alter the number of removed SLNs. In the era of healthcare spending scrutiny, the elimination of lymphoscintigraphy in this patient population may save money without altering technical outcomes.