In treating breast cancer, it is very important to know if the cancer has spread beyond the breast. The cancer most commonly spreads first to the lymph nodes in the axilla (armpit). In the past, while removing the cancerous breast tissue, surgeons would also remove all or most of the lymph nodes in and around the affected breast to determine if the cancer had spread. Unfortunately, this radical removal could lead to marked swelling of that arm and other complications in recovery from surgery.
Now a test called breast lymphoscintigraphy helps define more accurately exactly what tissue needs to be removed. This test locates the sentinel lymph node or nodes, so called because they are the first ones reached by fluids from the cancerous lesion and thus typically the first nodes to be affected by cancer spread. This sentinel node or nodes can then be sampled at the same time as the breast surgery, possibly limiting the amount of surgery to be done. If tumor cells have not yet traveled to the sentinel node, complete lymph node dissection and additional therapy (chemotherapy/radiation therapy) may be avoided.
On the day of surgery, the patient arrives at the hospital about 2 hours before the scheduled surgery time. A local anesthetic, lidocaine, is injected beneath the nipple of the involved breast, which may cause some localized burning in the injection site, but this should only last for a few seconds. Following the lidocaine injection, a radioactive tracer is injected that will move through the lymph system over the next few hours.
The patient arrives in surgery 2 hours after injection of the radioactive tracer. After anesthesia is administered, the surgeon also injects 2 to 5 cc of 1% isosulfan blue dye around the tumor site as an additional method of locating sentinel nodes. A hand-held gamma probe called a Neoprobe will be moved over the body to identify “hot” or radioactive lymph nodes. These nodes may also be stained blue because of the blue dye. Lymph nodes with high radiation counts and/or stained blue are considered sentinel nodes and will be removed and studied by the pathology department.
If the sentinel node or nodes do not contain cancerous material, the patient may be spared axillary dissection, which decreases the potential for complications such as arm swelling and nerve irritation.