Factors that affect the false negative rate of sentinel lymph node mapping with methylene blue dye alone in breast cancer

OBJECTIVE: This study aimed to investigate the clinicopathological factors of the false negative rate (FNR) and accuracy of sentinel lymph node biopsy (SLNB) mapping with 1% methylene blue dye (MBD) alone, and to examine how to reduce the FNR in patients with breast cancer. METHODS: A total of 365 patients with invasive breast carcinoma who received axillary lymph node dissection after SLNB were retrospectively analyzed. SLNB was performed with 2 to 5 mL of 1% MBD. We studied the clinicopathological factors that could affect the FNR of SLNB. RESULTS: The identification rate of sentinel lymph nodes (SLNs) was 98.3% (359/365) and the FNR of SLNB was 10.4% (16/154). Multivariate analysis showed that the number of dissected SLNs and metastatic lymph nodes were independent predictive factors for the FNR of SLNB. The FNR in patients with 1, 2, 3, and ≥4 SLNs was 23.53%, 15.79%, 3.85%, and 1.79%, respectively. CONCLUSIONS: SLNB mapping with MBD alone in patients with breast cancer can produce favorable identification rates. The FNR of SLNB decreases as the number of SLNs rises. Because of side effects of searching for additional SLNs and the FNR, removal of three or four SLNs may be appropriate.