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 (p