Relevance and methods of interventional breast sonography in preoperative axillary lymph node staging

Reduction of therapy-induced morbidity is an important goal for the improvement of the quality of breast cancer treatment. The introduction of sentinel lymph node biopsy (SLNB) significantly contributed to the reduction of surgery-induced morbidity in the shoulder-arm region. However, a clinically positive nodal status is still considered a contra-indication for SLNB. The current data constellation clearly shows that the clinical and also the sonographic malignancy assessment is insufficient for the accurate identification of the nodal status. A merely clinical and/or image-based appraisal of the axillary lymph node status would lead to overtreatment due to unnecessary axillary dissection in approximately 40 % of patients. In order to reduce the rate of unnecessary axillary dissection (AD), pretreatment interventional clarification is necessary to provide more detailed information about the histological condition of the lymph node. Comparing the currently available methods, fine needle aspiration (FNA) is the best in terms of cost and time requirement, practicability and complication rate. However, considering the sensitivity, it is inferior to ultrasound-guided core needle biopsy (CNB). Thus, a negative FNA outcome requires further clarification, which possibly can be performed with CNB. With a specificity of nearly 100 % and therefore a low rate of false positive cases for FNA, complete AD can be indicated by a positive FNA result. In the context of the interventional procedure, it must be stressed that FNA requires a high level of expertise on the part of both the examiner and the cytologist. The prerequisite for optimal interventional diagnostics of lymph nodes is an adequate sonographic assessment on the basis of standardized sonomorphological criteria.