Sentinel Lymph Node Biopsy and Primary Tumor Gene Expression Profiling in Finding Axillary Lymph Node Metastases in Women Who Have Received Neoadjuvant Therapy for Stage II, Stage III, or Stage IV Breast Cancer

RATIONALE: Sentinel lymph node biopsy and gene expression profiling of the primary breast tumor may help determine if tumor cells have spread to the axillary lymph nodes and help doctors plan more effective surgery for breast cancer. PURPOSE: This clinical trial is studying how well sentinel lymph node biopsy and primary tumor gene expression profiling work in finding lymph node metastases in women who have received neoadjuvant therapy for stage II, stage III, or stage IV breast cancer. OBJECTIVES: * Determine the efficacy of sentinel lymph node mapping for assessing axillary lymph node status after neoadjuvant therapy in women with stage II, III, or IV breast cancer. * Correlate gene expression profiling of the primary breast cancer with axillary and sentinel lymph node status in these patients. OUTLINE: This is a pilot study. After neoadjuvant chemotherapy, patients undergo sentinel lymph node (SLN) mapping comprising technetium Tc 99m sulfur colloid injected into the subareolar area to identify the SLN. Within 1-2 hours after injection, patients undergo SLN biopsy followed immediately by definitive local surgery comprising modified radical mastectomy or breast segmentectomy with axillary lymph node dissection. SLN and axillary lymph nodes are examined by hematoxylin and eosin (H \& E) staining for the presence or absence of metastases. If the lymph nodes are negative for tumor by H \& E, the lymph nodes are further analyzed by immunohistochemistry. The primary tumor is analyzed by microarray analysis for gene expression profile determinations. Patients are followed at 2-3 weeks after surgery. PROJECTED ACCRUAL: A total of 60 patients will be accrued for this study within 2-3 years.