Objective The aim of the present study was to determine how many sentinel lymph nodes (SLNs) are appropriate for predicting non-SLN metastasis in breast cancer. Methods The association between clinicopathological features and non-SLN metastasis was retrospectively analyzed in 472 patients who underwent axillary lymph node dissection (ALND) following SLN biopsy. Another 251 patients who underwent only SLN biopsy without ALND were analyzed and followed up for 2 years. Results A large tumor size, positive SLN, and HER-2 positivity were independent predictors of non-SLN metastasis. There were significant differences in non-SLN metastasis between patients with one negative SLN and patients with an absence of negative SLNs. There was no significant difference in non-SLN metastasis between patients with one negative SLN and two or more negative SLNs. The recurrence-free survival rate for patients who did not undergo ALND was 99.6% (245/246). Conclusion Surgeons should ensure that the number of SLNs obtained is appropriate. The presence of one negative SLN is enough in SLN biopsy. Considering the invasiveness of the surgery, two or more negative SLNs may be unnecessary.
Keywords: Breast cancer; axillary lymph node dissection; biopsy; metastasis; non-sentinel lymph node; sentinel lymph node.