Sentinel lymph node identification rates and axillary concordance can only be accurately determined by comparing 'like with like' injected materials.

Abstract

Despite the accepted status of sentinel lymph node biopsy (SLNB) as the standard for axillary staging in breast cancer patients with clinically and radiologically negative axillae pre-operatively, there is surprisingly still a lack of consensus on the most appropriate site of injection of radioactive tracer with or without blue dye. We discuss the article by Sadeghi et al. "Axillary concordance between superficial and deep sentinel node mapping material injections in breast cancer patients: systematic review and meta-analysis of the literature." Breast Cancer Res Treat 144(2): 213-222. Whilst in this study both comparison arms (superficial and deep injections) were in the same patients to ensure comparability of evaluated groups, this does limit the conclusions, which can be drawn from this study. It has meant that when comparing intra-operative sentinel lymph node (SLN) identification and concordance rates, it is not possible to compare 'like with like' at different injection sites (deep radioactive tracer vs superficial radioactive tracer; superficial blue dye vs deep blue dye). This leads to inaccurate conclusions due to the different properties of these materials. The only way to determine the optimal injection site of radioactive tracer and blue dye for SLN identification intra-operatively and accurate concordance rates is by direct comparisons of 'like with like' when it comes to injected materials at different injection sites.