The purpose of this study is to determine the detection rate and the false negative rate of sentinel lymph node (SLN) by superparamagnetic iron oxide (SPIO) alone or in addition to radioisotope and compared to the standard method (blue and radioisotope) after neoadjuvant chemotherapy in patients with node-positive breast cancer converted to node negative after treatment by ultrasound. A randomized controlled trial.

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.

Inclusion Criteria:

• Histologically proven primary invasive breast cancer with clinical stage T1 through T3, N1 through N2, M0 according to the American Joint Committee on Cancer (AJCC) Cancer Staging Manual, seventh edition
• Completed or were planning to undergo neoadjuvant chemotherapy
• Prechemotherapy axillary nodal disease confirmed by fine-needle aspiration or core-needle biopsy
• The axilla is clinically and radiologically (by ultrasound) negative (ycN0) postchemotherapy and before surgery
• Removal of at least two SLNs
• Signed informed consent from each patient before study entry

Exclusion Criteria:

• T4 tumors, cN3 or cM1
• The axilla is clinically and radiologically (by ultrasound) positive (ycN1) postchemotherapy
• Intolerance or hypersensitivity to the compounds or iron dextran or superparamagnetic iron oxide or to vital blue dye or radioactive product.
• Chronic iron overload
• Pacemaker or other metallic implantable device in the chest wall
• Failure to submit to medical study for geographical, social or psychological
• Patient deprived of liberty or under guardianship
• Pregnant or lactating