Identification of the sentinel lymph node(s) is accomplished by injecting blue dye, radioactive tracer, or both, into the breast prior to lumpectomy or mastectomy. The dye and/or tracer then travel into the armpit, and turn an average of two nodes bright blue, or radioactive when using tracer. These get removed via a small incision in the armpit and are thoroughly tested by a pathologist. This analysis will reveal whether or not cancer has spread from the breast to the lymph nodes. If cancer has not spread, the nodes are "negative", indicating early stage breast cancer. If cancer has spread to the nodes, the nodes are called “positive”, and additional treatments must be considered: further surgery, radiation, and chemotherapy. In response to an exciting discovery published in 2011 by Dr. Armando Giuliano, et.al., many surgeons no longer remove additional armpit lymph nodes even after cancer is found in the sentinel nodes. We now recommend only radiating the remaining nodes in patients with 1-2 positive lymph nodes. There is a 15 year survival benefit of performing an ALND in patients with 3-5 positive sentinel nodes. Prior to the era of sentinel lymph node biopsy, surgeons would remove all of the armpit lymph nodes to make sure the cancer did not spread. This procedure, called a complete axillary node dissection, resulted in complications in up to 84% of patients, including pain, numbness, arm swelling (lymphedema), fluid buildup (seroma), limited arm movement, and infection. A sentinel lymph node biopsy can reduce these complications to under 10%.