SCOUT Localization at Time of Lymph Node Biopsy

To evaluate the utility of SCOUT radar localization (SCOUT) placement at the time of axillary lymph node (LN) biopsy.

A retrospective study was conducted on SCOUT placement during axillary LN core-needle biopsy (CNB) between January 2018 and September 2023. The SCOUT was considered utilized if detected and removed during targeted axillary dissection with or without subsequent axillary LN dissection. Analysis was performed with a Fisher's exact test and Wilcoxon rank-sum test to determine association of features with either LN disease status or SCOUT utilization.

SCOUT placement was performed in 127 patients during US-guided CNB, with 77% (98/127) malignant and 23% (29/127) benign results. Three patients were lost to follow-up and excluded. SCOUTs placed during LN biopsy were utilized in 70% (87/124) of patients. A total of 104 patients underwent axillary surgery, including 80 malignant and 24 benign CNB specimen cases. The SCOUT-localized node did not take up blue dye or radiotracer in 28% (22/80) of patients with malignant CNB LNs, 86% (19/22) of whom were in postneoadjuvant treatment. SCOUTs were not utilized for 30% (37/124) of patients. Age was a significant predictor of SCOUT utilization, with 87% (40/46) of utilization among patients <50 years old (P <.001). Among the 24 patients with benign CNB specimens who underwent axillary surgery, 25% (6/24) had nodal metastasis, of which 50% (3/6) were within the SCOUT-localized node.

SCOUTs placed at the time of LN biopsy facilitate detection of the biopsied node and may be particularly beneficial after neoadjuvant treatment and in women <50 years old.