Concordance of Peritumoral Technetium 99M Colloid and Subareolar Blue Dye Injection in Breast Cancer Sentinel Lymph Node Biopsy

Introduction Sentinel lymph node (SLN) mapping has emerged as a less invasive method for axillary lymph node staging in patients with breast cancer. Blue dye and radioisotopes are commonly used agents to localize SLNs, but the optimal site for the injection of these agents continues to be debated. In this study, we evaluated whether subareolar injection of blue dye led to the identification of the same SLNs as peritumoral injection of technetium colloid. Methods From March 2003 to August 2006, 124 patients with invasive breast cancer, diagnosed by core needle biopsy, were included in this study. Demographic and clinical data were abstracted from medical records. Approximately 1 h prior to surgery, all patients had peritumoral injection of 37 Mbq of Tc-99m-sulfur colloid. In the operating room, 3 to 5 mL of 1% lymphazurin was injected into the subareolar area. SLNs were categorized as radio-labeled-only, blue-only, or radio-labeled + blue. Data were analyzed with 95% exact confidence intervals, Spearman rank coefficient and κ coefficient. Results The mean number of SLNs identified was 1.9 (range 1–5). With the combination of two methods 122 out of 124 patients (98.4%) had successful identification of SLNs. One hundred fifteen patients (92.7%) had SLNs that were blue and 121 patients (97.6%) had radio-labeled SLNs. One hundred fourteen patients had at least one SLN that was both blue and radio-labeled, yielding a concordance rate of 91.9% (95% CI, 0.88–0.98). Metastatic disease was identified in SLNs of 28 patients. All lymph nodes with evidence of metastasis were both blue and radio-labeled. Conclusions Our study showed a high degree of concordance between subareolar blue dye and peritumoral radiocolloid in identification of SLNs. These results further support that the breast parenchyma and subareolar plexus drain to similar SLNs within the axilla. These two techniques can complement each other in localizing SLNs with a high success rate.