3.5 Outcome Analysis: Patients with positive axillary nodes on dissection and positive SNB and/or PET will be considered true positive (TP) for that modality. A negative axillary dissection and negative PET and/or SNB will identify the true negative (TN) group. A positive axillary dissection and negative PET and/or SNB will identify the false negative (FN) subgroup. A negative axillary dissection and positive PET and/or SNB will identify the false positive (FP) subgroup. Sensitivity (TP/TP + FN) and specificity (TN/TN + FP) will be determined. If patients do not have successful sentinel node surgery or PET scanning, they will be included in the analysis of the individual modality which was successful.