Sentinel Lymph Node After Neoadjuvant Chemotherapy in Breast Carcinoma

GANEA3 is a prospective multicenter diagnostic study assessing the benefit of targeting initial involved node in complement to SLND and breast tumor characteristics to predict axillary status after NAC. The diagnostic performances of this strategy will be primarily assessed by the decrease of the FNR with the combined strategy compared to SLND alone. The primary objective is to evaluate the interest of identifying, before NAC, the initial involved lymph node to improve the prediction of axillary status after NAC. The main secondary objectives are : * To assess the feasibility, at the time of the surgery, of the identification and resection of the initially involved lymph node, tagged with the metal clip before NAC ; * To evaluate the complications related to the setting up of the metal clip for the identification of a lymph node metastatic ; * To evaluate the interest and impact of immunohistochemical analysis of tagged lymph node and SLN ; Patients treated for a large early breast cancer (BC) needing NAC undergo axillary sonography assessment routinely performed to seek suspicious nodes. When several suspicious nodes are found only the worst is chosen. A fine needle aspiration is performed to allow cytological examination (biopsy is optional) of the suspicious node. In case of proven axillary involvement, the patient is informed about GANEA 3 study in order to be included. At this step the patient must accept the study and sign the consent form. The involved node is then tagged (with a metal clip) under sonography. In case of multiple suspicious nodes, the radiologist must choose the worst node in order to tag only one involved node. Then, then patients will perform their chemotherapy. The choice of NAC regimen is let at the discretion of each participating team. After NAC, breast tumor size and axillary assessment are performed. Breast and axillary surgery are performed during the same procedure, 4 to 6 weeks after completion of NAC. Breast surgery can be conservative or radical. All patients undergo the resection of the tagged axillary node, SLN biopsy and a complementary axillary lymphadenectomy.