E15: National Variation in Implementation of Sentinel Lymph Node Biopsy for Clinically-Node Positive Patients Undergoing Neoadjuvant Therapy

Introduction: Multiple clinical trials have demonstrated the feasibility of sentinel lymph node biopsy (SLNB) for axillary staging in patients with clinically node-positive (cN+) breast cancer who receive neoadjuvant chemotherapy (NAC). For patients with an excellent clinical response to NAC, SLNB offers the potential to avoid the morbidity associated with an axillary lymph node dissection (ALND). In these trials, an acceptable false negative rate for SLNB after NAC has been achieved with different technical considerations, including the use of dual tracer mapping and the removal of ≥3 SLNs. To evaluate the implementation of this trial data into practice, we evaluated trends in axillary staging in cN+ patients who received NAC, adherence to recommendations for removal of ≥3 SLNs, and variation in SLN yield between facilities.

Methods: We performed a retrospective cohort study using the National Cancer Database of women with cN1-cN2 disease who received NAC. We determined trends in axillary staging (SLNB alone, SLNB followed by ALND, or ALND alone) from 2012-2020. The number of SLNs examined and facility variation in adherence to removal of ≥3 SLNs were evaluated from 2018-2020. All estimates were reliability adjusted with a mixed model with random clustering effect by hospital.

Results: 81,831 women with cN1-cN2 disease who received NAC were evaluated. From 2012-2020, patients receiving SLNB alone increased from 9.5% to 36.7%, SLNB followed by ALND increased from 15.5% to 28.2%, and ALND alone decreased from 68.9% to 28.3%. From 2018-2020, 64.7% of patients had ≥3 SLNs evaluated, with no significant change in lymph node yield over time. We observed significant interfacility variation in SLN yield, with rates of obtaining ≥3 SLNs ranging from 37.8% to 86.7% (mean [SD], 64.7 [8.2]).

Conclusions: From 2012-2020, there has been significant de-escalation of axillary surgery in patients with cN+ breast cancer following NAC, with the majority of patients currently avoiding ALND. However, adherence to national guidelines recommending the removal of ≥3 SLNs demonstrates an opportunity for even further de-escalation, with approximately a third of patients potentially receiving inadequate staging. Significant interfacility variation demonstrates a performance gap and an opportunity for improvement in operative technique, potentially through the implementation of the Commission on Cancer Operative Standards to improve surgical quality and further reduce need for ALND.