Sentinel Node Biopsy Following NeoAdjuvant Chemotherapy in Biopsy Proven Node Positive Breast Cancer

Conditions for patient eligibility Inclusion criteria: * Patients must be female. * Patients must be 18 years of age or older. * Patients with stage IIA, IIB, IIIA (T1-3 and N1-2) breast cancer. Clinical N0 accepted if biopsy proven node disease. * Patients that have biopsy proven positive axillary disease made by core needle biopsy or fine needle aspiration . * Patients that accept to undergo neoadjuvant chemotherapy; patients are eligible until the day of surgery. * Patients with bilateral breast cancer are eligible. Sentinel node biopsy is allowed on the contralateral breast if there is no disease in the axilla prior to chemotherapy. * Patients that understand, accept and have signed the approved consent form. Exclusion Criteria: * Patients with inflammatory breast cancer. * Patient with stage IIIB, IIIC or IV breast cancer (T4 and N3) Patients with clinical N3 disease are excluded. * Patients that have had previous axillary dissection or an axillary sentinel node biopsy; (patients that have had excisional biopsy or ipsilateral tumorectomy are eligible). * Patients that have had previous radiotherapy to the axillary nodes * Patients that have had mammary reduction * Patients that are medically unfit to receive chemotherapy, as evaluated by the treating physician. * If the injection of blue dye is planned, patients with hypersensitivity or allergy to isosulfan blue, Patent blue or methylene blue or radiocolloid dye are ineligible. * Patients who are pregnant or breast feeding . * Psychiatric or addictive disorders or other conditions that preclude the patient from meeting the study requirements.