Axillary Management in Breast Cancer Patients With Needle Biopsy Proven Nodal Metastases After Neoadjuvant Chemotherapy

Inclusion Criteria: * Age ≥ 18 * Male or female * cT1-3N1M0 breast cancer at diagnosis (prior to NACT) as per AJCC 8th edition (see Section 6.4.1) o Patients with occult primary invasive breast cancer (no identifiable invasive cancer in the breast) with FNA or core biopsy proven nodal metastases are eligible for the study. * FNA or core biopsy confirmed axillary nodal metastases at presentation * Oestrogen receptor and HER2 status evaluated on primary tumour * Received standard NACT as per local guidelines (Patients undergoing neoadjuvant endocrine therapy as part of another clinical trial are eligible) * Imaging of the axilla, as required, to assess response to NACT (per local guidelines) * Undergo a dual tracer sentinel node biopsy (SNB) after NACT with at least 3 nodes removed. * If a single tracer SNB is performed: the patient is eligible only if the involved node is marked before or during NACT, and at least 3 nodes (including the marked node) are removed during sentinel node biopsy. * If the node is not marked or the marked node is not removed: the patient is eligible only if the histology report shows evidence of down-staging with complete pathological response e.g., fibrosis or scarring in at least one node and at least 3 nodes removed. * If fewer than 3 nodes are found on histology: the patient is eligible only if BOTH points a) and b), below, are met: 1. involved node was marked and removed during SNB; and 2. removed marked node shows evidence of downstaging on histology e.g. fibrosis or scarring. * If the sentinel node(s) cannot be localised on SNB: axillary node sampling should be performed, the patient will be eligible if at least 3 nodes are removed. * No evidence of nodal metastases post NACT (isolated tumour cells, micro or macro metastasis) * Patients with complete pathological response in the axilla but residual disease in the breast post NACT are eligible for the study * Patients who are cN0 (node negative) at initial presentation, with a negative sentinel node post NACT showing evidence of treatment response or downstaging will be eligible, provided at least 3 nodes are removed. 5.2. Exclusion Criteria Participants will be excluded if they have any one of the following: * Bilateral synchronous invasive breast cancer * Sentinel node biopsy prior to NACT * Previous axillary nodal surgery on the same body side as the scheduled targeted sampling * Any previous cancer within last 5 years or concomitant malignancy except * basal or squamous cell carcinoma of the skin * in situ carcinoma of the cervix * in situ or stage 1 melanoma * contra- or ipsilateral in situ breast cancer * chronic lymphocytic leukaemia not on treatment