Abstract P1-03-04: Factors Influencing Additional Nodal Disease and Pathologic Nodal Upstaging with Axillary Dissection in Patients Breast cancer related lymphedema rates following sentinel lymph node biopsy: how concerned should patients and clinici

Abstract Background: Breast cancer-related lymphedema (BCRL) is a feared side effect following nodal surgery and breast cancer treatments. While long-term rates of BCRL after axillary lymph node dissection are known, little and highly variable historical data exists on rates following sentinel lymph node biopsy (SLNB). Since our institution has been prospectively utilizing bioimpedance spectroscopy (BIS) for screening and early-detection of lymphedema, we sought to examinate the incidence of BCRL following SLNB to help guide patient discussions regarding surgical risks, adjuvant treatment decisions, and the optimal method for long-term lymphedema surveillance. Methods: A retrospective review of a prospectively maintained, single institution, breast cancer database was performed. All patients underwent SLNB between 11/2014-11/2017. BIS measurements were obtained on all patients preoperatively, postoperatively, and then every 3 months for 1 year, every 6 months for 1 year, then annually. BIS > 3 standard deviations above preoperative baseline was considered abnormal. Any abnormal reading was followed up with a repeat measurement one month later. Patients who received adjuvant radiotherapy and/or chemotherapy, and those who had a recent surgical procedure, were only diagnosed with BCRL if a repeat BIS four weeks later was still abnormal. Additionally, BCRL diagnosis resulted in clinical evaluation and initiation of self-directed home interventions with subsequent reassessment for resolution versus persistent BCRL (pBCRL). Groups were compared using t-tests or Wilcoxon rank sum tests for continuous variables and chi-square or Fisher’s exact tests for categorical variables. Analyses used R (version 4.2.1) and p<0.05 was statistically significant. Results: A total of 324 patients underwent SLNB and had both pre-operative and post-operative BIS measurements. A single abnormal BIS occurred in 58 (18%) patients. Of these, 41 (71%) returned to baseline on BIS reassessment without intervention and were therefore not diagnosed with lymphedema. Of the 17 patients (5%) with confirmed BCRL, 15 (88%) had stage 0 lymphedema and only two had stage 1 lymphedema at diagnosis. After self-directed home interventions, only two patients had pBCRL for a pBCRL rate of 0.6% for all patients following SLNB. Development of pBCRL was not associated with age (p=0.39), BMI (p=1.00), receipt of radiotherapy (p=0.52), receipt of taxane chemotherapy (p=1.00 ), or the number of nodes examined (p=0.40). However, the average number of positive nodes was statistically significant for the development of pBCRL (p=0.01). Conclusions: The incidence of BCRL among patients undergoing SLNB is low. When identified early, at-home interventions can be employed and pBCRL is extremely uncommon. The only risk factor associated with the development of pBCRL following SLNB is the average number of positive nodes. We speculate that increasing nodal disease burden is associated with more frequent use of adjuvant nodal radiotherapy and systemic therapy, both of which are known to contribute to risk of BCRL. It is important to recognize that isolated abnormal BIS measurements are not uncommon, and that the majority of these instances reflect intermittent fluctuations in BIS that do not reflect BCRL. Repeat BIS should be performed before BCRL is diagnosed. Clinicians should be aware of the extremely low incidence of pBCRL when determining surveillance models and counseling patients on the risks and benefits of SLNB, especially because foregoing SLNB may impact adjuvant treatment recommendations. Citation Format: Lyndsey Kilgore, Tateum Mattingly, Sabrina Korentager, Shane R Stecklein, Kelsey E Larson, Christa R Balanoff, Elizabeth J Jeffers, Lynn Hinton, Jordan Baker, Jamie L Wagner. Factors Influencing Additional Nodal Disease and Pathologic Nodal Upstaging with Axillary Dissection in Patients Breast cancer related lymphedema rates following sentinel lymph node biopsy: how concerned should patients and clinicians be? [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2024; 2024 Dec 10-13; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(12 Suppl):Abstract nr P1-03-04.