The indocyanine green method is equivalent to the 99mTc-labeled radiotracer method for identifying the sentinel node in breast cancer: A concordance and validation study

Abstract

The aim of this study was to assess concordance between the indocyanine green (ICG) method and (99m)Tc-radiotracer method to identify the sentinel node (SN) in breast cancer. Evidence supports the feasibility and efficacy of the ICG to identify the SN, however this method has not been prospectively compared with the gold-standard radiotracer method in terms of SN detection rate. Between June 2011 and January 2013, 134 women with clinically node-negative early breast cancer received subdermal/peritumoral injection of (99m)Tc-labeled tracer for lymphoscintigraphy, followed by intraoperative injection of ICG for fluorescence detection of SNs using an exciting light source combined with a camera. In all patients, SNs were first identified by the fluorescence method (ICG-positive) and removed. A gamma ray-detecting probe was then used to determine whether ICG-positive SNs were hot ((99m)Tc-positive) and to identify and remove any (99m)Tc-positive (ICG-negative) SNs remaining in the axilla. The study was powered to perform an equivalence analysis. The 134 patients provided 246 SNs, detected by one or both methods. 1, 2 and 3 SNs, respectively, were detected, removed and examined in 70 (52.2%), 39 (29.1%) and 17 (12.7%) patients; 4-10 SNs were detected and examined in the remaining 8 patients. The two methods were concordant for 230/246 (93.5%) SNs and discordant for 16 (6.5%) SNs. The ICG method detected 99.6% of all SNs. Fluorescent lymphangiography with ICG allows easy identification of axillary SNs, at a frequency not inferior to that of radiotracer, and can be used alone to reliably identify SNs.