Sentinel Lymph Node Biopsy in Breast Cancer Patients Undergoing Neo-Adjuvant Chemotherapy: Clinical Experience with Node-Negative and Node-Positive Disease Prior to Systemic Therapy

SIMPLE SUMMARY: Axillary status is crucial for determining the correct local and systemic treatment. The possibility of de-escalating axillary surgery in patients with breast cancer undergoing neo-adjuvant chemotherapy is controversial. This is especially true for clinically node-positive (cN+) patients, for whom axillary lymph node dissection still represents the gold standard, in contrast to clinically node-negative (cN0) patients, for whom sentinel lymph node biopsy has become more widely accepted. Several studies have recently shown that a minimally invasive surgical approach of the axilla is safe in cN+ patients who become cN0 after neo-adjuvant chemotherapy, raising new questions about the potential benefit of this strategy. This retrospective study is aimed at assessing the reliability of this approach by comparing the characteristics and oncological outcomes (e.g., overall survival) of cN0 and cN+ patients before neo-adjuvant chemotherapy and axillary surgery type. ABSTRACT: Background: Sentinel lymph node biopsy (SLNB) has emerged as the standard procedure to replace axillary lymph node dissection (ALND) in breast cancer (BC) patients undergoing neo-adjuvant chemotherapy (NAC). SLNB is accepted in clinically node-negative (cN0) patients; however, its role in clinically node-positive (cN+) patients is debatable. Methods: We performed a retrospective analysis of BC patients undergoing NAC and SLNB. Our aim was to evaluate the clinical significance of SLNB in the setting of NAC. This was accomplished by comparing the characteristics and oncological outcomes between cN0 and cN+ patients prior to NAC and type of axillary surgery. Results: A total of 291 patients were included in the analysis: 131 were cN0 and 160 were cN+ who became ycN0 after NAC. At a median follow-up of 43 months, axillary recurrence occurred in three cN0 (2.3%) and two cN+ (1.3%) patients. However, there were no statistically significant differences in oncological outcomes (disease-free survival, distant disease-free survival, overall survival, and breast-cancer-specific survival) between cN0 and cN+ patients nor between patients treated with SLNB only or ALND. Conclusions: SLNB in the setting of NAC is an acceptable procedure with a general good prognosis and low axillary failure rates for both cN0 and cN+ patients.