Risk factors for a false-negative result of sentinel node biopsy in patients with clinically node-negative breast cancer

Purpose Although sentinel lymph node biopsy (SLNB) can accurately represent the axillary lymph node (ALN) status, the false-negative rate (FNR) of SLNB is the main concern in the patients who receive SLNB alone instead of ALN dissection (ALND). Materials and Methods We analyzed 1,886 patients who underwent ALND after negative results of SLNB, retrospectively. A logistic regression analysis was used to identify risk factors associated with a falsenegative (FN) result. Cox regression model was used to estimate the hazard ratio of factors affecting disease-free survival (DFS). Results Tumor located in the upper outer portion of the breast, lymphovascular invasion, suspicious node in imaging assessment and less than three sentinel lymph nodes (SLNs) were significant independent risk factors for FN in SLNB conferring an adjusted odds ratio of 2.10 (95% confidence interval [CI], 1.30 to 3.39), 2.69 (95% CI, 1.47 to 4.91), 2.59 (95% CI, 1.62 to 4.14), and 2.39 (95% CI, 1.45 to 3.95), respectively. The prognostic factors affecting DFS were tumor size larger than 2 cm (hazard ratio [HR], 1.86; 95% CI, 1.17 to 2.96) and FN of SLNB (HR, 2.51; 95% CI, 1.42 to 4.42) in SLN-negative group (FN and true-negative), but in ALN-positive group (FN and true-positive), FN of SLNB (HR, 0.64; 95% CI, 0.33 to 1.25) did not affect DFS. Conclusion In patients with risk factors for a FN such as suspicious node in imaging assessment, upper outer breast cancer, less than three harvested nodes, we need attention to find another metastatic focus in non-SLNs during the operation. It may contribute to provide an exact prognosis and optimizing adjuvant treatments.