Audit of Targeted Sentinel Node Biopsy (TSNB) in Patients With Limited Nodal Disease Undergoing Primary Surgery

Axillary ultrasound scan (AUS) is routinely employed in the UK for preoperative axillary staging and can diagnose approximately 50 - 80% of node positive patients when combined with percutaneous needle biopsy techniques (either core-biopsy or fine-needle aspiration cytology). It is recognised that nodal burden is generally higher in clinically node negative patients with abnormal nodes on AUS and confirmed on needle-biopsy to be histologically positive than patients diagnosed as node positive on sentinel node biopsy (SNB). However, up to 40% of biopsy-proven node positive patients are found to have fewer than 3 involved nodes on subsequent axillary lymph node dissection (ALND) and are potential candidates for less extensive axillary surgery with axillary radiotherapy (ART) rather than ALND. The total number of abnormal nodes on ultrasound is a key predictor of overall nodal tumour burden. The AMAROS and OTOASOR trials randomised patients with up to 2 positive sentinel nodes to either ALND or ART. These trials were conducted around the turn of the millennium and before routine use of AUS and therefore would have included a significant number of patients who were radiologically node positive (cN1). Likewise, the ACOSOG Z0011 trial that randomised a similar group of patients to either ALND or observation only, did not incorporate routine AUS and would have included some (radiological) cN1 patients. These trials revealed no adverse impact on disease-free or overall survival from omission of completion ALND. Targeted axillary dissection (TAD) was introduced a few years ago to reduce the false negative rate of SNB following neoadjuvant chemotherapy (NACT) and has been standardised as part of the ongoing ATNEC trial \[ClinicalTrials.govNCT04109079\]. This technique for axillary staging after NACT is increasingly being adopted in the UK and elsewhere. TAD is technically more straightforward and less challenging in patients undergoing primary surgery with no concerns about clip migration consequent to nodal shrinkage as part of treatment response to NACT. Furthermore, the risk of under-treating the axilla is offset by the protocol: if no disease is identified in the targeted nodes (false-negative case), then patients proceed to ALND, thereby ensuring adequate treatment. Unlike TAD following NACT, the presence of viable tumour within the sampled nodes is mandatory and finding fibrosis is irrelevant except as a response to nodal biopsy per se. Current ASCO guidelines support both SNB and TAD as staging options for patients with ultrasound-detected, biopsy-confirmed nodal disease. The Edinburgh randomised trials comparing four-node sampling with ALND demonstrated significantly lower arm morbidity with node sampling, supporting TAD as a less morbid appropriate alternative in this patient population. The UK-ANZ POSNOC trial randomised 1,900 patients with \

Inclusion Criteria: * cT1-2N1M0 breast cancer\* * FNA or core biopsy confirmed axillary nodal metastases * ≤2 abnormal nodes on imaging * Undergo a dual tracer or single tracer sentinel node biopsy along with removal of the marked node (Targeted Sentinel Node Biopsy, TSNB) * 1 or 2 macrometastases identified in the removed nodes, with at least three nodes removed * If the sentinel node(s) cannot be localised on SNB: axillary node sampling should be performed, the patient will be eligible if 1 or 2 macrometastases are identified in the removed nodes, with at least three nodes removed. * If the node is not marked or the marked node is not removed, the patient will be eligible if 1 or 2 macrometastases are identified in the removed nodes, with at least three nodes removed‡. * patients with T3 tumours on post-operative histology will remain eligible. For multifocal/multicentric tumours, the T stage is based on the size of the largest invasive tumour focus rather than the combined size of all tumours. * If \