Refining the Performance of Sentinel Lymph Node Biopsy Post-neoadjuvant Chemotherapy in Patients with Pathologically Proven Pre-treatment Node-positive Breast Cancer: An Update for Clinical Practice.

Background: Neoadjuvant chemotherapy (NAC) has become the standard treatment regimen for locally advanced breast cancer and has recently been incorporated into the treatment of early breast cancer. It allows down-staging of tumors favoring breast-conservative surgery over mastectomy. Furthermore, NAC results in nodal conversion in about 40% of patients. This favorable outcome has complicated the decision-making regarding the best approach in managing the axilla post-treatment; especially in pathologically proven nodal disease prior to NAC. Axillary lymph node clearance is still the standard-of-care for this group of patients; however, it is clearly an over-treatment in a substantial number of patients. Given the high accuracy of sentinel lymph node biopsy (SLNB) post-NAC in clinically node-negative cases prior to treatment, substantial research has been carried out in order to validate the feasibility of post-NAC SLNB in pathologically proven node-positive cases. The results so far are still inconclusive, yet promising.

Materials And Methods: We performed a computer-aided review of the literature for relevant articles on the performance of SLNB post-NAC in pathologically proven node-positive patients prior to chemotherapy. We also targeted studies on important factors that can refine the accuracy of SLNB in this group of patients, as well as elements favoring pathological complete response. All studies focusing on post-NAC SLNB in pre-treatment node-positive cases including randomized controlled trials, retrospective and prospective series, review articles, and two meta-analyses were included.

Results: The review established a false-negative rate of 14-15.1% and an IR of 89-92.3%. Several technical enhancements, as well as imaging modalities, may be incorporated to improve the performance of SLNB. Furthermore, selected patients with more likelihood of pathological complete response represent the best candidates for this technique.

Conclusion: SLNB is a valid option after NAC in patients with pathologically proven node-positive breast cancer, given the high node-conversion rate. The literature demonstrated a false-negative rate that is slightly higher than that of patients initially node-negative which although might increase the locoregional recurrence in theory, has no effect on chemotherapy-decision making, and will most probably have no impact on overall survival. We identified several measures to refine its accuracy.