Improved False-Negative Rates Using a Novel Patient Selection Flowchart in Initially Biopsy-Proven Node-Positive Breast Cancer undergoing Blue-Dye Alone Guided Sentinel Lymph Node Biopsy After Neoadjuvant Chemotherapy

Abstract Purpose: Current trials support the application of sentinel lymph node biopsy (SLNB) in node-positive breast cancer treated with neoadjuvant chemotherapy (NAC) with a lower false negative rate (FNR) if dual-tracer (radioisotope and blue-dye) is used. However, radioisotopes are not available in many areas of the world. In this study, we evaluated the feasibility and accuracy of SLNB mapped with methylene-blue-dye alone. Methods: This study enrolled 132 patients with biopsy-proven node-positive breast cancer with a clip placed in the positive node who then received NAC. After chemotherapy and before operation, all patients underwent axillary ultrasound (AUS) assessment and were classified as either negative (AUS-) or positive (AUS+) according to the axillary status. All patients underwent both SLNB and axillary lymph node dissection (ALND). SLNB was mapped with methylene-blue-dye alone. FNRs were evaluated on factors potentially affecting false-negative SLN finding.Results: Using methylene-blue-dye alone, the FNR of SLNB was 9.9%. Post-NAC AUS assessment (p=0.009), number of SLNs retrieved (p=0.029), and the retrieved of the clipped node (p=0.086), showed association with FNRs in multivariate analysis. In AUS- group, FNR was as low as 2.5%. In AUS+ group, retrieving ≥4 SLNs including the clipped node improved FNR from 17.1% to 4.8%. A flowchart was designed with the combination of post-NAC AUS assessment, retrieved SLN number, and the retrieved of clipped node further improve overall FNR to 3.3%. Conclusion: In biopsy-proven node-positive breast cancer treated with NAC, using a flowchart to optimize patient selection reduces the FNR of single-tracer (methylene-blue-dye) guided SLNB.