Prognosis according to clinical and pathologic lymph node status in breast cancer patients who underwent sentinel lymph node biopsy alone after neoadjuvant therapy.

This study aimed to evaluate the prognosis of breast cancer patients who received neoadjuvant chemotherapy and underwent sentinel lymph node biopsy (SLNB) alone as axillary surgery regardless of their clinical and pathological lymph node status. We reviewed the records of 1,795 patients from Asan Medical Center who were diagnosed with stage I-III breast cancer and received neoadjuvant chemotherapy during 2003-2014. We selected 760 patients who underwent SLNB alone as axillary surgery and divided these patients into four groups according to their clinical lymph node (cN) and pathological lymph node (pN) status: cN(-)pN(-) (n = 377), cN(-)pN(+) (n = 33), cN(+)pN(-) (n = 242), and cN(+)pN(+) (n = 108). We then compared axillary lymph node recurrence, locoregional recurrence (LRR), distant metastasis-free survival (DMFS), and overall survival (OS) among the four groups using Kaplan-Meier analysis. We compared prognosis between the cN(-)pN(-) and cN(+)pN(-) groups to determine whether SLNB alone is an adequate treatment modality even in patients with cN positive pathology before neoadjuvant therapy but SLNB-negative pathology after NAC. The 5-year axillary recurrence rates in the cN(-)pN(-) and cN(+)pN(-) groups were 1.4% and 2.9%, respectively, and there was no significant difference between the two groups (p = 0.152). The axillary recurrence and LRR rates were significantly different among the four groups, with the pN-negative groups (cN[-]pN[-], cN[+]pN[-]) showing lower recurrence rates. DMFS and OS were also significantly different among the four groups, with the cN negative groups (cN[-]pN[-], cN[-]pN[+]) showing improved survival rates. Our study findings suggest that SLNB alone was associated with lower LRR rates even in patients with cN positive pathology before neoadjuvant therapy but cN negative pathology after SLNB. Moreover, recurrence and survival rates differ significantly according to clinical and pathological lymph node status.