Phase 2, open-label study of AVB-620 in women with primary, nonrecurrent, nonmetastatic breast cancer undergoing either a lumpectomy with simultaneous sentinel lymph node biopsy (SLNB) or axillary lymph node dissection (ALND), or a mastectomy and simultaneous ALND. AVB-620 is a synthetic protease-activated peptide dye conjugate administered intravenously for the fluorescence detection and localization of potentially malignant tissue in primary tumor, tumor margins, or lymph nodes. A fluorescence image will be displayed on a monitor and will assist the surgeon to assess potentially cancerous tissue within the primary tumor site, tumor margins, or in lymph nodes which drain the primary tumor site.