Long-term survival after sentinel lymph node biopsy or axillary lymph node dissection in pN0 breast cancer patients: a population-based study

Purpose Findings from randomized clinical trials have shown that survival in patients with sentinel lymph node (SLN)-negative breast cancer is noninferior with SLN biopsy (SLNB) alone versus further axillary lymph node dissection (ALND). However, the long-term outcome of these two surgical approaches in pN0 breast cancer patients in real-world setting remains uncertain. Methods We included patients diagnosed with pathologically staged T1-2N0M0 breast cancer between 2000 and 2015 in surveillance, epidemiology, and end results 18-registry database. Patients were considered to have undergone SLNB alone if they had ≤ 5 examined lymph nodes (ELNs), and ALND if they had ≥ 10 ELNs. The outcomes included overall survival (OS) and breast cancer-specific survival. Propensity score analyses by weighting and matching and multivariable Cox regression analysis were performed to minimize treatment selection bias. Results We included 309,430 patients (253,501 SLNB and 55,929 ALND). In the weighted cohort, ALND was associated with significantly lower OS (hazard ratio [HR] 1.13; 95% confidence interval [CI] 1.10–1.16) and BCSS (HR 1.16; 95% CI 1.10–1.22) compared with SLNB alone. Both the propensity score-matching model and multivariable Cox model demonstrated a survival benefit for SLNB when compared with ALND. Subgroup analyses for key variables did not change these findings. Conclusion We found statistically significant differences in OS and BCSS between SLNB and ALND, though the magnitude of these differences was small. Our findings further support that SLNB alone should be the standard of care for patients who do not have metastatic lymph nodes identified during breast cancer surgery.