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PPS30. Expanding the utilization of upfront sentinel lymph node biopsy in clinically node positive patients with estrogen receptor positive breast cancer

Friday, March 6, 2026
3:40 PM - 4:10 PM MST
Location: HUB Poster Park - West Hall 1-3
Introduction: Patients who present with clinically node-positive ER+/HER2- breast cancers may have low volume nodal disease. While NCCN guidelines endorse upfront sentinel lymph node biopsy (SLNB) for patients with expected limited nodal disease diagnosed by imaging, many patients still undergo upfront axillary lymph node dissection (ALND). We hypothesize that some patients could be spared ALND by performing upfront SLNB.


Methods:

Patients ≥18 years of age with ER+/HER2-, cT1-3 cN1 M0 breast cancer, undergoing upfront surgery from 2012-2021 were selected from the National Cancer Database. Logistic regression identified factors associated with change in nodal category and Cox proportional hazards models estimated adjusted overall survival (OS).


Results:

There were 54,404 patients included. Of these patients, axillary staging with SLNB alone was performed in 17.3% (975/5642) in 2012 compared to 31.8% (1765/5554) in 2021. Adjusted OS did not differ significantly by type of breast surgery (p=0.26) or axillary surgery (p=0.29). Patients receiving SLNB alone had lower grade, lower clinical and pathologic T-category (Table 1). Patients undergoing SLNB alone were more likely to downstage to pN0 (18.8%) or remain pN1 (75.5%) as opposed to upstage to pN2-3 (5.7%), whereas 39.2% of patients undergoing ALND upstaged to pN2-3. In the SLNB group, a median of 3 nodes were examined, with 44.2% having 4+ nodes examined. In the ALND group, 67.2% had ALND as the initial staging procedure without a preceding SLNB. 44.1% of patients who underwent ALND had only 1-2 positive nodes. Characteristics associated with higher odds of pathologic nodal upstaging included lobular carcinoma vs. ductal (OR 1.82, p< 0.001), higher cT category (cT3 vs. cT1 OR 2.14, p< 0.001), or higher grade (grade 3 vs. 1 OR 1.74, p< 0.001).


Conclusions:

This study demonstrates increasing use of upfront SLNB in ER+/HER2- cN1 disease over time. Many patients undergoing ALND have limited nodal involvement suggesting that ALND may have been safely avoided.  These findings suggest that select cN1 patients with limited nodal disease likely derive little benefit from ALND and it may be reasonable to consider upfront SLNB.

Learning Objectives:

  • ER+/HER2-, cN1 patients may have limited nodal disease and upfront SLNB may offer an opportunity to safely avoid ALND in patients who confirm 1-2 positive nodes on SLNB.
  • In ER ER+/HER2-, cN1 patients, identify characteristics associated with higher odds of pathologic nodal upstaging.