Surgical Breast Oncology Fellow Mayo Clinic Rochester, Minnesota, United States
Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.
Participants should be aware of the following financial/non-financial relationships:
Stacy B. Sanders, MD, MS, MHA: I do not have any relevant financial / non-financial relationships with any proprietary interests.
Introduction: Sentinel lymph node (SLN) surgery is used for staging after neoadjuvant chemotherapy (NAC). In patients with a +SLN, completion axillary dissection (cALND) is recommended. We sought to evaluate factors impacting positive non-SLNs (NSLNs) and nodal burden after NAC in patients with +SLN and cALND by clinicopathologic factors.
Methods: We identified all patients at our hospital between 2006-2021 with a +SLN ( >0.2mm) following NAC who underwent cALND. Rates of +NSLN on cALND were compared by SLN metastasis size. Chi-square tests and multivariable logistic regression were used to assess factors predictive of +NSLN.
Results: 219 patients (167 cN+, 52 cN0 prior to NAC) with +SLN(s) after NAC underwent cALND. Median patient age was 51 years. 27 (12.3%) had SLN micromets and 192 (87.7%) had SLN macromets. Additional NSLN disease was found in 126/219 (57.5%) including 25/52 (48.1%) of cN0 and 101/167 (60.5%) of cN+ patients.
Patients with SLN micromets were less likely to have +NSLN(s) than those with SLN macromets (37.0% vs 60.4%, p=0.02). Final pN category was lower in SLN micromet [ypN1mi in 14/27 (51.9%), ypN1a-c in 7/27 (25.9%), ypN2 in 5/27 (18.5%) and ypN3 in 1/27 (3.7%)] than SLN macromet [ypN1mi in 0/192, ypN1a-c in 117/192 (60.9%), ypN2 in 50/192 (26.0%), and ypN3 in 25/192 (13.0%), p< 0.001].
Among cN+ patients, +NSLN rate was 31.8% with SLN micromets vs 64.8% with SLN macromets (p=0.003). Final pathologic N category also significantly differed by size of SLN metastasis (see figure). On univariate analysis, factors predictive of +NSLN included SLN met size, biologic subtype (HR+/HER2- vs TNBC vs HER2+, 69% vs 54.5% vs 31%, p< 0.001), and number of +SLN (p=0.01). Grade and T-category were not significant. Factors associated with +NSLN on multivariate analysis were SLN metastasis size category (OR 3.33) and HER2 status (OR 3.90).
Conclusions: Rates of nodal positivity on cALND in the setting of +SLN after NAC are high, supporting the current standard of routine cALND. NSLN positivity varies by tumor biology and SLN met size, indicating these factors should be considered when counseling patients and considering omission of cALND.
Learning Objectives:
Describe the rate of additional nodal disease found on completion ALND for patients found to have a +SLN following NAC
Understand how sentinel lymph node metastasis size and tumor biology influence rates of additional non-SLN involvement on completion ALND after NAC
Appreciate .how final pathologic N stage varies as a function of SLN metastasis size
