Abstract PS2-01-10: De-escalation of sentinel lymph node biopsy beyond the Choosing Wisely guidelines

Abstract Background: The Choosing Wisely (CW) campaign issued by the Society of Surgical Oncology recommends omitting sentinel lymph node biopsy (SLNB) in women over age 70 with early-stage hormone receptor (HR) positive, HER2 negative breast cancer. The publication of the SOUND and INSEMA trials recently expanded indications for considering the omission of SLNB in younger women. We hypothesized that the rate of omission of SLNB has increased over time. Our primary objective was to define predictors of omitting SLNB and secondarily, to determine the incidence of patients beyond the CW population having omission of SLNB. Methods: We utilized the National Cancer Database (NCDB) to query between 2018-2021 for patients with cT1 or cT2 invasive breast cancer treated with breast surgery without use of neoadjuvant therapy. We recorded surgical procedure types, biomarkers, grade, the number of clinical and pathologic positive nodes, Charlson-Deyo Score, race/ethnicity, age, urban/rural setting, histology, and academic/community setting. Univariate analysis with the Pearson’s Chi-squared test and multivariable analysis with logistic regression were performed to identify factors associated with omission of SLNB. Univariate analysis was also performed to identify variables associated with rates of breast conserving surgery (BCS) versus mastectomy. Results: Overall, 433,737 patients met study inclusion criteria with 313,201 (72%) treated with BCS while 120,536 (28%) were treated with mastectomy. In our cohort, 133,169 (31%) were over age 70 and 368,228 (86%) were HR+/HER2-. Only 4219 patients (1%) had omission of SLNB, of which 3599 (88%) were HR+/HER2-, 247 (6.0%) were HER2+, and 238 (5.8%) were triple negative. Omission of SLNB did not increase over time with rates ranging from 0.06%-1.6% of the overall study population by year. On multivariable analysis, predictors of omitting SLNB were age 70 (OR 1.51, CI 0.86-0.97), non-zero Charlson-Deyo Score (p0.001), HR+/HER2- (OR 1.09, CI 1.06-1.13), year of diagnosis 2021 (OR 1.56, HR 1.52-1.6), non-lobular histology (p0.001), academic setting (p0.001), and metropolitan setting (p0.001). White race was associated with omitting SLNB but was only marginally significant on univariate analysis (p=0.047). Type of surgery as BCS was associated with omission of SLNB (p0.001) on univariate analysis only. Most patients who had omission of SLNB had cT1 disease (n=3409 or 83% of patients having no nodal surgery while fewer patients with cT2 status had no nodal procedure (n=722, 17%), p0.001). Of patients having no SLNB, 98% were cN0, 2% were cN1, 0.2% were cN2 and 0.1% were cN3. Conclusions: Rates of the omission of SLNB did not increase over time from 2018-2021 despite the publication of the Choosing Wisely recommendations in 2016 to consider omitting SLNB in patients over age 70 with HR positive, HER2 negative early-stage breast cancer. Only 1% of breast cancer patients had omission of SLNB despite 31% of the cohort being over age 70. Age 70, non-zero Charlson-Deyo Score, HR+/HER2- status, year of diagnosis 2021, non-lobular histology, academic and metropolitan setting were associated with omission of SLNB. These data provide estimates that may be used in the future to compare the impact of the SOUND and INSEMA trial on rates of omission of SLNB based on prospective randomized controlled trials that expand criteria for omission of SLNB beyond the Choosing Wisely guidelines. Citation Format: T. Cheung, S. Patil, M. Nelis, S. A. Valente, J. E. Lang. De-escalation of sentinel lymph node biopsy beyond the Choosing Wisely guidelines abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS2-01-10.