Determining axillary nodal status at the time of diagnosis is paramount for optimal staging and treatment planning. SLNB is indicated for patients with a clinical and radiological negative axilla. 25%-43% of breast cancer patients are reported to present with radiologically suspicious axillary lymph nodes at the time of diagnosis. In these patients, a pre-operative ultrasound-guided needle sampling of suspicious axillary lymph tissue is indicated.
This can rationalize patient care by identifying those with axillary metastases using merely a minimally-invasive intervention. These patients can be counselled with regards to proceeding directly to definitive axillary surgery in the form of axillary lymph node dissection (ALND) rather than sentinel node biopsy (SLNB), thereby omitting a potentially unnecessary surgical procedure. Patients with a negative axillary status can proceed to SLNB for definitive nodal status determination. Furthermore, in the paradigm of neoadjuvant treatment, confirming a histopathologic involvement of lymph nodes by US-guided needle biopsies enables for decision on neoadjuvant chemotherapy without the need for a surgical procedure.
The main challenge in performing CNB (Core Needle Biopsy) within the axilla is to avoid damaging the major vessels and nerves. Technical, operator and procedural requirements that mitigate risks in CNB sampling of the axilla have been reported in the literature. It is suggested that the operator shall fully acknowledge the detailed anatomy including vessels and nerves in the axilla, have good hand-eye coordination as well as be experienced in US-guided interventions. Proper positioning of the patient is reported to be important. Color Doppler ultrasound shall be used to assess the location of large vessels relative to the intended biopsy track and to avoid sampling a vascular component of the node. Perfect guiding and visualization of the needle tip at all times is reported to be essential. It is suggested that a biopsy device with a controllable needle action is safer to use. Omitting the firing action gives the operator greater control over the final needle tip placement.
Due to the difficulty of the procedure there may be inclusion bias in the reported studies. In one series, patients presenting with nodes adjacent to a vessel or located very deep and difficult to access were not asked to participate in the study and hence not subjected to CNB. In another study FNA (Fine Needle Aspiration) was performed instead of CNB when the lymph nodes were in close proximity to vessels. A recent German survey showed that merely 79% of breast centers (41/52) perform biopsies in the axilla (data on file), and anecdotal evidence suggests that in certain departments only the most experienced physician performs CNB procedures in axillary lymph nodes, risking economic/operational inefficiencies.
For the purpose of documenting the prevalence and composition of cases deemed challenging in this study, an experienced expert panel has compiled a comprehensive list of risk parameters characterizing the anatomic complexity and procedural difficulty of axillary lymph node needle biopsies.
Recently a new biopsy device indicated for the use in breast and axillary lymph nodes (NeoNavia biopsy system, NeoDynamics, Sweden) has become available. It incorporates a pneumatic needle insertion mechanism that is intended to provide better control of needle progression and enable stepwise insertion without noticeable deformation or displacement of surrounding tissue as visualized under ultrasound. Furthermore a new method of tissue acquisition is employed that has pre-clinically shown a higher sampling yield compared to CNB. These characteristics indicate that the device could be well suited for tackling even the most challenging cases of axillary lymph node biopsies. Initial clinical results indicate that in axillary lesions deemed "technically difficult", i.e. where prior US-guided biopsies with CNB or FNA had yielded non-diagnostic histology results, the NeoNavia device performed successfully thereby significantly altering clinical management.
