Role of Sentinel Node Surgery in Identifying Candidates for Adjuvant CDK4/6 Inhibitors: Implications of Choosing Wisely and ASCO Omission Criteria

INTRODUCTION: Recent trials have expanded eligibility for omission of sentinel lymph node biopsy (SLNB) in early-stage breast cancer, while adjuvant cyclin-dependent kinase 4/6 (CDK4/6) inhibitors improve outcomes in patients with high-risk features that often rely on pathologic nodal status. The impact of SLNB omission on identifying candidates for CDK4/6 inhibitor therapy remains unclear. We evaluated how omission affects eligibility under Choosing Wisely and American Society of Clinical Oncology (ASCO) criteria. METHODS: From the National Cancer Database (2018-2022), we identified women aged ≥ 50 years with hormone-receptor-positive, HER2-negative, clinical T1-2N0M0 breast cancer treated with upfront surgery and SLNB. Omission-eligible cohorts were defined based on Choosing Wisely and ASCO criteria. CDK4/6 inhibitor (abemaciclib and ribociclib) eligibility was assessed using tumor features alone (modeling omission), SLNB findings, and axillary lymph node dissection (ALND) findings. Multivariable logistic regression identified predictors of SLNB determining eligibility. RESULTS: Among 150,629 patients, 73% met SLNB omission criteria. Positive SLNs were found in 9-10%, and only 2% had pN2-3 disease. SLNB omission would miss 4% (abemaciclib) and 8% (ribociclib) of eligible patients in the Choosing Wisely cohort, and 1 and 8%, respectively, in the ASCO cohort. ALND increased candidacy by only 1%. Approximately 13 SLNBs were required to identify one CDK4/6-eligible patient, and 299 SLNBs were required to identify one patient expected to derive a 5-year invasive disease-free survival benefit. CONCLUSIONS: SLNB omission excludes few patients eligible for adjuvant CDK4/6 inhibitor therapy. These findings support shared decision-making and suggest SLNB should not be performed solely to determine CDK4/6 eligibility.