Axillary Reverse Mapping in Clinically Node-Positive Breast Cancer Patients

SIMPLE SUMMARY: Axillary reverse mapping (ARM) nodes are involved in a significant proportion of clinically node-positive (cN+) breast cancer patients. However, neoadjuvant chemotherapy (NAC) is effective at decreasing the incidence of nodal metastases in cN+ patients. In the present study, the rates of involvement of ARM nodes in the NAC group were significantly lower than those of the upfront surgery group (36.6% vs. 62.2%, p < 0.01). Despite the lower incidence of metastases in ARM nodes in the NAC group, the rate was still too high to warrant the sparing of ARM nodes. On the other hand, (18)F-FDG-PET/CT was useful to detect a low risk of ARM node metastases after NAC, but it was still not suitable to detect residual metastatic disease of the axilla. Therefore, suspicious ARM nodes must be removed even in the ARM procedure, while it is important to spare ARM lymphatics in order to minimize arm lymphedema. ABSTRACT: Background: Axillary reverse mapping (ARM) nodes are involved in a significant proportion of clinically node-positive (cN+) breast cancer patients. However, neoadjuvant chemotherapy (NAC) is effective at decreasing the incidence of nodal metastases in cN+ patients. Patients and methods: One hundred forty-five cN+ patients with confirmed nodal involvement on ultrasound-guided fine needle aspiration cytology were enrolled in this study: one group underwent axillary lymph node dissection (ALND) without NAC (upfront surgery group), and the other group underwent ALND following NAC (NAC group). The patients underwent (18)F-FDG-positron emission tomography/computed tomography ((18)F-FDG-PET/CT) before surgery, as well as an ARM procedure during ALND. Results: the rates of involvement of ARM nodes in the NAC group were significantly lower than those of the upfront surgery group (36.6% vs. 62.2%, p < 0.01). Notably, involvement was significantly decreased after NAC in non-luminal-type tumors as compared to the luminal-type (18.4% vs. 48.5%: p < 0.01). Moreover, there was a significant difference in ARM node involvement after NAC between patients with or without axillary uptake of (18)F-FDG (61.5% vs. 32.5%: p < 0.01). Conclusions: NAC significantly decreased the risk of ARM node metastases in cN+ patients, but (18)F-FDG-PET/CT was not suitable to detect residual metastatic disease of the axilla after NAC.