Retrospective Cohort Study on the Long-term Oncologic Outcomes of Sentinel Lymph Node Mapping Methods (Dye-Only versus Dye and Radioisotope Mapping) in Early Breast Cancer: A Propensity Score-Matched Analysis

PURPOSE: In sentinel lymph node (SLN) biopsy (SLNB) during breast cancer surgery, SLN mapping using dye and isotope (DUAL) may have lower false-negative rates than the dye-only (DYE) method. However, the long-term outcomes of either method are unclear. We aimed to compare long-term oncological outcomes of DYE and DUAL for SLNB in early breast cancer. MATERIALS AND METHODS: This retrospective single-institution cohort study included 5,795 patients (DYE, 2,323; DUAL, 3,472) with clinically node-negative breast cancer who underwent SLNB and no neoadjuvant therapy. Indigo carmine was used for the dye method and Tc99m-antimony trisulfate for the isotope. To compare long-term outcomes, pathologic N0 patients were selected from both groups, and propensity score matching (PSM), considering age, pT category, breast surgery, and adjuvant treatment, was performed (1,441 patients in each group). RESULTS: The median follow-up duration was 8.7 years. The median number of harvested sentinel nodes was 3.21 and 3.12 in the DYE and DUAL groups, respectively (p=0.112). The lymph node–positive rate was not significantly different between the two groups in subgroups of similar tumor sizes (p > 0.05). Multivariate logistic regression revealed that the mapping method was not significantly associated with the lymph node–positive rate (p=0.758). After PSM, the 5-year axillary recurrence rate (DYE 0.8% vs. DUAL 0.6%, p=0.096), and 5-year disease-free survival (DYE 93.9% vs. DUAL 93.7%, p=0.402) were similar between the two groups. CONCLUSION: Dye alone for SLNB was not inferior to dual mapping regarding long-term oncological outcomes in early breast cancer.