Localizing Positive Axillary Lymph Nodes in Breast Cancer Patients Post Neoadjuvant Therapy.

INTRODUCTION

Multiple trials demonstrated the feasibility of sentinel lymph node biopsy (SLNB) after neoadjuvant chemotherapy. Those trials reported > 10% false-negative rate; however, a subset analysis of the Z1071 trial demonstrated that removing the clipped positive lymph node (LN) during SLNB reduces the false-negative rate to 6.8% post neoadjuvant chemotherapy. This study examines the factors that might contribute to the ability to identify the clipped nodes post neoadjuvant therapy (NAT).

MATERIALS AND METHODS

Breast cancer patients with biopsy-proven metastatic axillary LN who underwent NAT, converted to N0, had preoperative localization, and then SLNB between 2018 and 2020 at a single institution were identified. A retrospective chart review was performed. Demographic and preoperative variables were compared between localization and nonlocalization groups.

RESULTS

Eighty patients who met inclusion criteria were included. A total of 39 patients were localized after NAT completion (49%). Only half of the patients with ultrasound-detectable marker clips were able to be localized. Minimal LN abnormality was seen in imaging after NAT completion in 39 patients and is significantly associated with localization; 26 (67%) were localized (Odds Ratio 4.31, P = 0.002, 95% Confidence Interval 1.69-10.98).

CONCLUSIONS

Our study suggests that radiologically abnormal LNs on preoperative imaging after NAT completion are more likely to be localized. Nodes that ultimately normalize by imaging criteria remain a significant challenge to localize, and thus localization before starting NAT is suggested. A better technology is needed for LN localization after prolonged NAT for best accuracy and avoids repeated procedures.