Omission of Sentinel Lymph Node Biopsy Among Women Aged 50 to 70 With Early-Stage Breast Cancer: Applying an Updated ASCO Guideline to a Real-World Population.

Abstract

Recent practice-changing guidelines from the American Society of Clinical Oncology (ASCO) recommend the omission of sentinel lymph node biopsy (SLNB) in patients over the age of 50 with early-stage breast cancer. We aimed to evaluate the association of clinicopathologic factors with sentinel lymph node positivity (SLN+) and the association of SLN+ with adjuvant therapy recommendation in this population. A single-institution retrospective cohort study of patients aged 50 to 70 years with early-stage invasive breast cancer (cT1N0, grade 1-2, estrogen receptor-positive, human epidermal growth factor receptor 2 negative (HER2-)) between 2022 and 2024 who underwent SLNB. Preoperative axillary ultrasound was not required. The univariate relationship between covariates and SLN+ was assessed using Fisher's exact test or logistic regression, followed by multivariable logistic regression. Fisher's exact test was also used to evaluate the relationship between SLN+ and receipt of adjuvant therapy. Two-year disease-free survival was estimated using the Kaplan-Meier method. Among 268 patients meeting the new ASCO Guideline criteria, the average age was 62 years (SD, 5.1). The majority had ductal histology (81.0%), pathologic T1 disease (94.8%), and grade 1 disease (51.5%). Adjuvant therapy included endocrine therapy (86.9%), whole breast radiation therapy (WBRT) (73.1%), partial breast radiation therapy (19.4%), chemotherapy (5.6%), and cyclin-dependent kinase 4/6 inhibitor (0.7%). SLN was positive in 15 (5.6%) patients (8 pN1mi, 7 pN1a). Factors statistically significantly associated with SLN+ included pathologic tumor category (P = .006) and 21-gene recurrence score (P < .001). An SLN+ result potentially impacted adjuvant recommendations for 11 patients (4.1%): 1 with a low 21-gene recurrence score received chemotherapy, 1 received a cyclin-dependent kinase 4/6 inhibitor, and 9 were eligible for partial breast radiation and received WBRT. With a median follow-up of 24.0 months, 2-year disease-free survival was 98% (95% CI, 96.1%-99.9%). In patients aged 50 to 70 years meeting the 2025 ASCO Guideline for SLNB omission, SLN+ was infrequent. Adjuvant treatment recommendations were unchanged in >95% of patients, due in part to information from other factors, such as recurrence score.