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QS4. Validation of ASCO guideline for omission of sentinel lymph node biopsy in postmenopausal women with early-stage breast cancer and negative preoperative axillary ultrasound: a two-year, single-institution retrospective review

Thursday, March 5, 2026
10:19 AM - 10:23 AM MST
Location: Breast/Endocrine HUB Zone
Introduction: ASCO no longer recommends routine sentinel lymph node biopsy (SLNB) in select patients who are p</span>ostmenopausal, ≥50 years old with negative preoperative axillary ultrasound (AUS) for grade 1-2, ≤2 cm, hormone receptor (HR) positive, HER2-negative invasive breast cancers undergoing breast-conservation (BCT).   To validate this new guideline, we assessed the rate of SLNB positivity, and the impact nodal staging may have on recommended adjuvant therapies.  


Methods: Single-institution, retrospective review of patients from January 1, 2023 to December 31, 2024. Inclusion criteria: age ≥50 years, T1N0 unifocal invasive carcinoma, grade 1-2, HR +, HER2-negative, negative AUS, and underwent BCT.  Multivariable logistic regression was used to evaluate 1) the association between tumor characteristics, patient demographics, and SLN positivity; 2) the association between SLN positivity and adjuvant therapies.  Odds ratio and its 95% CI was estimated for each covariate in the model. P< 0.05 was considered statistically significant. 


Results: 260 women were included for analysis: mean age 62.3 years and mean tumor size was 12.6 mm. Figure 1 includes patient demographic and tumor characteristics as well as multivariable analysis results. 21 (8.1%) patients had a positive SLN. One patient (0.4%) had 4 positive SLNs. Three patients underwent axillary lymph node dissection. Multivariable analysis showed larger tumor size [OR 1.19 (1.09-1.30), p< 0.001] and younger age [OR 0.90, (0.83-0.98), p=0.015] were significantly associated SLN positivity. On separate multivariable analysis, SLN positivity was statistically predictive of adjuvant regional nodal irradiation (RNI) [OR 157178 (41.6-5.9E8), P=0.004] but no other adjuvant therapies. Univariable regression analysis showed a higher Oncotype score to be significantly associated with adjuvant CDK 4/6 inhibitor (CDKi) [OR 1.19 (1.03-1.36), p=0.012] and chemotherapy use [OR 1.9 (1.3-2.75) p</span>=0.004]. 


Conclusions: Applying the ASCO guideline retrospectively, 8.1% of patients who met criteria for omission were found to have node positive disease. SLN positivity was predictive of adjuvant RNI only and no systemic therapies. Genomic profiling via Oncotype was predictive of adjuvant CDKi and chemotherapy use despite nodal staging. These findings support the new ASCO guideline as there was no change to systemic therapy recommendations with positive SLNB.  

Learning Objectives:

  • See validation of the new ASCO guidelines for omission of sentinel lymph node biopsy in early stage breast cancer with negative axillary ultrasound
  • See the association between tumor characteristics and sentinel lymph node positivity to identify potential predictors of nodal involvement
  • see what variables were significantly associated with systemic therapy recommendations