Clinical impact of breast MRI with regard to axillary reverse mapping in clinically node positive breast cancer patients following neo-adjuvant chemotherapy

Background: Axillary reverse mapping (ARM) is a technique that discerns axillary lymphatic drainage of the arm from the breast. In the current study, we retrospectively evaluated the incidence of metastatic axillary lymph node involvement, including ARM lymph nodes, in clinically node positive breast cancer patients (cN+ patients) in whom neo-adjuvant chemotherapy (NAC) was administered followed by primary ALND using breast MRI.
Patients and methods: Data from 98 cN+ breast cancer patients were analysed retrospectively. Patients without residual axillary disease at breast MRI following NAC (RAD−, n = 64) were compared with patients with residual axillary disease (RAD+, n = 34). Presence of suspect axillary lymph nodes on pre-NAC and post-NAC breast MRI was determined by experienced breast radiologists and was correlated to histopathological findings.
Results: In the RAD-group residual axillary disease on pathological analysis following NAC was found in 25 patients (39.1%), as compared to 24 patients (70.6%) in the RAD + group (p = 0.003). Metastatic involvement of ARM lymph nodes following NAC was demonstrated in 5 patients (7.8%) in the RAD-group as compared to 10 patients (29.4%) in the RAD + group (p = 0.005).
Conclusion: Breast MRI following NAC is not suitable to detect residual metastatic disease of the axilla. However, breast MRI post-NAC may be of use to identify cN+ patients with a low risk of ARM lymph node metastases. This may help to select a subgroup of cN+ patients in whom sparing of ARM lymph nodes during axillary lymph node dissection can be considered