Lymph Node Positivity of Axillary Reverse Mapping Lymph Nodes at the Time of Axillary Lymph Node Dissection: Two-Site Prospective Trial

Background Axillary reverse mapping (ARM) was introduced in 2007 to identify and selectively preserve upper-extremity lymphatics during axillary lymph node surgery to decrease the risk of lymphedema. The patient population in which an ARM lymph node (LN) can be preserved during an axillary lymph node dissection (ALND) has not been established to date. This study aimed to determine the frequency of metastatic involvement of an ARM LN among patients undergoing ALND. Methods Patients undergoing ALND with or without immediate lymphatic reconstruction (ILR) were enrolled in a prospective trial at two institutional sites between April 2018 and Decemeber 2022. This report analyzes the ARM node positivity and total LN positivity rates during ALND for the cohort of patients enrolled in the ILR intervention arm of the study. Results The inclusion criteria were met by 139 patients, who made up the study population (133 with breast cancer and 6 with other disease). Of the breast cancer patients, 99.2% were female, 35.3% (47/133) were cT3 or greater, and 96.2% (128/133) had cN1 or greater disease. For 55 of the 133 patients (41.4%), the ARM nodes were marked and specified in the pathology report. Of the 55 patients, 39 (70.9%) had a positive LN at ALND. Of these 55 patients, 11 (20%) had positive ARM nodes. The ARM LN was the only positive node in 3 of the 11 patients. Conclusion In the contemporary patient population undergoing ALND, the positivity rate of the ARM LN was relatively high, suggesting that leaving ARM LNs in patients undergoing ALND may not be oncologically safe.