Sentinel Node Biopsy: Better Detection for Early Micrometastisis

A Sentinel Node biopsy is a fairly new technique that allows patients to undergo a less invasive surgical procedure in comparison to what was the standard lymph node dissection. The purpose of testing the lymph nodes is for detection of micrometastatic disease in cancers such as melanoma, breast cancer and many others. If in fact the sentinel node proves to be positive for micrometastic cancer then the surgeons will perform a full dissection. Performing a sentinel node biopsy prevents patients from having to endure a full dissection unless it is absolutely necessary.

There is long term side affects associated with a full dissection and they include lymphedema (LIM-fuh-DEE-muh) and nerve damage. Prior to the sentinel node biopsy procedure the patients at highest risk for lymph node involvement would have the full dissection. If determined that there was no evidence of micro metastases they underwent the procedure only to experience long term complications from the procedure. In a traditional full lymph node dissection, the pathologist receives several lymph nodes. It is not possible for the pathologist to detect which one is the sentinel lymph node in the standard full dissection.

Definitions of some of the key words discussed:
(Definitions from www.cancer.gov)
What are lymph nodes?
Lymph nodes are small round glands. They filter through bacteria/germs from the blood stream. They can be found in the groin, neck, and under the arm pit.

Metastasize-To spread from one part of the body to another. When cancer cells metastasize and form secondary tumors, the cells in the metastasis tumor are like those in the original (primary) tumor.

Lymphedema -A condition in which excess fluid collects in tissue and causes swelling. It may occur in the arm or leg after lymph vessels or lymph nodes in the underarm or groin are removed or treated with radiation.

Lymph node dissection - A surgical procedure where the lymph nodes are removed and examined to see whether they contain cancer. For a regional lymph node dissection, some of the lymph nodes in the tumor area are removed; for a radical lymph node dissection, most or all of the lymph nodes in the tumor area are removed. Also referred to as lymphadenectomy.

Lymphatic mapping - The use of dyes and radioactive substances to identify lymph nodes that may contain tumor cells. Also called lymph node mapping.

Lymphatic mapping takes place about 1 hour prior to the sentinel node biopsy. A radioactive blue dye is injected adjacent to the tumor site in an effort to map the path the dye takes in the lymphatic system. The surgeon utilizes a gamma probe to pick up the areas with highest level of radioactivity. The first lymph node this dye reaches will be considered the sentinel node. Once the area is determined the surgeon will begin the surgery and remove the lymph node. The lymph node is then sent off to a pathology lab to be studied for the presence cancer cells that have metastasized (meh-TAS-ta-size) to the lymphatic system. If micro metastases are present according to the pathology results a formal lymph node dissection would then be necessary.

There are many advantages of a sentinel node biopsy. Recuperation time is generally a few days. You will not need a drain, or physical therapy. You can begin your normal activities within about a week. The procedure is an out patient procedure and you will go home the same day it is performed. This procedure can possibly get a more accurate assessment of whether the cancer has spread to the lymph nodes. A sentinel node biopsy procedure results in critical results to determine further treatment options with the least possible surgery for the patient.

According to some of the recent research this procedure is 10-15% more reliable if both the dye and the radioactive tracer are used, rather than if only one of these two techniques is performed.

Some questions you may want to ask your surgeon:

1.How many sentinel node dissections have you performed?

2.What are my treatment options if the lymph node shows cancer?

3.Will you be using dye and radioactive tracer?

A sentinel lymph node biopsy that shows no evidence of cancer indicates a >95% chance that the remaining lymph nodes in the area are free from cancer also. Therefore, there is no need to undergo a full lymph node dissection. The presence of cancer in the lymph nodes is one of the most important factors your doctor will consider when determining how aggressive your treatment will need to be. Early detection of cancer spread to the lymph nodes can possibly prolong the patient's lives and could in some cases cure the patient.