Abstract PD7-08: Less is not necessarily more: A propensity matched national analysis on effect and outcome of sentinel lymph node biopsy omission

Background: Routine sentinel lymph node biopsy (SLNB) has been recommended against by Choosing Wisely© Foundation due to its low value in clinical node negative, hormone receptor positive breast cancer patients age≥70 years old. We used the National Cancer Database (NCDB) to examine the effect of SLNB omission and outcomes in this population. We hypothesized that SLNB would be beneficial in this population.Methods: The National Cancer Database was queried for women diagnosed with primary unilateral invasive clinical stage T1N0M0 hormone receptor positive, HER-2 negative breast cancer from 2012-2017. Patients age ≥ 70 years old with Charlson Score ≥1 who underwent partial mastectomy and received hormonal therapy were included in the study cohort. Patients received neoadjuvant therapy or underwent upfront axillary lymph node dissection (ALND) were excluded. A 1:3 propensity match with replacement was performed to compare SLNB omission vs. SLNB group controlling age, race, comorbidities, insurance and facility. Overall survival was analyzed using stratified multivariable Cox proportional hazard regression analysis.Results: Of 14,150 patients, 1,928 (13.6%) omitted SLNB and 12,222 (86.4%) underwent SLNB, including 1,545/12,222 (12.6%) who proceeded to ALND. Central portion tumor location (OR=1.77, P=0.001), clinical T1c (OR= 2.49, P Citation Format: Lifen Cao, Megan E Miller, Luke D Rothermel, Alberto J Montero, Christopher W Towe, Robert Shenk. Less is not necessarily more: A propensity matched national analysis on effect and outcome of sentinel lymph node biopsy omission [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD7-08.