Sentinel Lymph Node Mapping

Sentinel lymph node mapping and biopsy is the best way to find out if breast cancer cells have escaped the original tumor and spread to nearby lymph nodes in the armpit. Sentinel lymph node mapping and biopsy is usually performed as part of breast cancer surgery. Although most women with a small breast tumor do not have cancer cells that have metastasized (spread) to lymph nodes, identifying which women do have armpit (axillary) lymph node involvement is important because it helps the medical and radiation oncologists plan additional treatment.

"Sentinel" refers to the first lymph node(s) in the armpit on the same side of the body as the breast cancer. Since specific lymph nodes handle drainage from the breast, this node(s) is the most likely place tumor cells will metastasize if some cells have left the original tumor by the time of surgery.

The advantage of sentinel lymph node mapping and biopsy is that it is a less invasive way to obtain information about possible breast cancer spread. However, a woman who has known cancer spread to her lymph node(s) that has been confirmed prior to surgery is not a candidate for the mapping procedure - these women need to undergo axillary dissection, a somewhat more extensive surgery to the armpit area that removes the lymph nodes known to contain cancer and additional lymph nodes in the same area to make as certain as possible that all cancer-containing lymph nodes have been eliminated.

Important Note

It is important to keep in mind that even if the sentinel lymph node(s) do not contain any escaped breast cancer cells, this does not guarantee that no cancer cells have traveled to another part of the body, like the bones or liver. But studies show that women with breast cancer who undergo lymph node biopsy that does not reveal any cancer cells in their lymph nodes have a reduced risk of breast cancer recurrence.

Sentinel Lymph Node Mapping Procedure

Sentinel lymph node mapping begins with a Breast Diagnostic Center radiologist injecting a very weak radioactive and blue dye solution into the cancerous area in the breast. The injection must be done at least an hour before surgery so that the solution has time to drain from the breast to the sentinel node(s). The isotope dye solution travels via the lymphatic system and marks the specific lymph nodes most likely to contain cancer cells if any metastasis has occurred.

After injection of the mapping solution and needle localization (if indicated), you are transported by hospital mini-bus to the pre-surgery area in the main hospital. Loved ones who are accompanying the patient may also travel to the hospital via the mini-bus.

In the OR

In the operating room the surgeon uses a Geiger counter and the dye to locate the sentinel node(s). A small incision is made so that these nodes can be removed and sent to the pathology department for immediate frozen section biopsy to determine if any cancer cells are present. If no cancerous cells are found, it is a good indicator the cancer has not spread out of the breast. However, if cancer cells are found in a sentinel lymph node, the standard of care is for the surgeon to proceed with an axillary dissection (surgical removal of additional lymph nodes in the armpit to make as certain as possible that all lymph nodes containing cancer have been eliminated).

Advantages of Sentinel Lymph Node Biopsy

Before the development of the sentinel lymph node mapping procedure, the only available method to check for presence of cancer in the lymph nodes was a more invasive axillary dissection. Unfortunately, axillary dissection includes a greater risk of side effects, including pain, nerve damage and chronic swelling of the arm. Although sentinel lymph node biopsy does not completely eliminate the risk of these side effects, the likelihood of a persistent problem is greatly reduced.

After Sentinel Lymph Node Mapping

For a day or so after sentinel lymph node mapping, the body eliminates the blue dye through urination. Although the urine typically appears blue to green, the dye is harmless to the kidneys and urinary system. The patient can help the body eliminate the dye by drinking plenty of fluids.

Questions ?

If you would like more information about sentinel lymph node mapping, or any other aspect of breast surgery, ask your breast surgeon or contact the Breast Navigator RNs at the Breast Diagnostic Center or the Advance Practice Nurses at Torrance Memorial Cancer Resource Center at 310-517-4665.