Sentinel Lymph Node Biopsy With Superparamagnetic Iron Oxide for Breast Cancer Patients After Neoadjuvant Treatment.

Identification of Sentinel node: * Arm 1 (Tc+blue dye): Identification of SLN using the standard technique of sub-areolar injection of technetium-99m (Tc-99m) and vital blue dye before surgery. * Arm 2 (Tc+SPIO): Identification of SLN using standard isotope technique of sub-areolar injection of technetium-99m (Tc-99m) before surgery and the magnetic technique with the sub-areolar injection of SPIO (Sienna+®) before surgery and detection with the SentiMag® probe. (Study) * Arm 3 (SPIO alone): Identification of SLN using the magnetic technique with the sub-areolar injection of SPIO (Sienna+®) before surgery and detection with the SentiMag® probe. (Study) Sentinel node's excision of radioactive and / or blue and / or magnetic (colored brown-brown), detection guided by hand probe gamma radiation, colorimetric and / or and SentiMag® paramagnetic probe. Lymph nodes that are radioactive, blue, magnetic or palpable are considered SLNs and are resected and submitted for pathological analysis. The protocol required that at least 2 SLNs to be resected. In all cases a completion axillary lymphadenectomy nodes dissection (ALND) will be performed after SLN biopsy. All SLNs will be excised and submitted before performing the ALND. Characterization of the nodal status of patients with the detection rate and the false negative rate of SLN for each arm.