Sentinel Lymph Node Biopsy

When a woman is diagnosed with breast cancer, doctors must determine the extent to which the disease has spread. Answers lie in the lymph nodes under the arm.

The presence of cancer in the first lymph node, the sentinel lymph node, helps sound the warning that the cancer has spread. With an important procedure called a Sentinel Lymph Node Biopsy, doctors can determine the best treatment and gain information that ultimately may reduce the amount of surgery needed.

Genesis, through its Center for Breast Health, was one of the first hospitals in the country to participate in a study of the effectiveness of sentinel lymph node biopsy, which now is an accepted standard of care for women diagnosed with breast cancer.

The procedure also has fewer side effects than a standard, more-invasive lymph node removal.

Sentinel lymph nodes

Pea-sized lymph nodes are part of the body’s lymphatic system – a series of small channels that drain excess fluid from all the tissues of the body back into the bloodstream.  As the fluid drains, it passes through the lymph nodes, which act as biologic filters, trapping bacteria, cancer cells or other cellular debris. The nodes then facilitate an immune system response to trapped particles.

Lymphatic fluid from the breast drains predominantly into lymph nodes located in the axilla, the area under the arm. In general, the fluid travels through lymph nodes in a step-wise fashion, so nodes located in an “upstream” position are the first to “see” the fluid as it leaves the breast.

“The sentinel lymph nodes located in the underarm are the first nodes to receive lymph drainage from the breast and the most likely nodes to contain cancer cells from a breast tumor if cancer has spread from the primary tumor,” said Dr. Aanestad.

“During a sentinel lymph node biopsy, an average of one to three sentinel lymph nodes is identified. If the sentinel lymph nodes do not contain cancer, there is a greater than 95 percent chance that the remaining axillary lymph nodes are also cancer-free.”

The procedure provides a faster and accurate assessment of whether the cancer has spread to the lymph nodes.

A complete axillary lymph node dissection removes most of the lymph nodes under the arm. All of the harvested nodes are then evaluated for evidence of cancer spread. Sentinel lymph node biopsy allows the surgeon to precisely identify the few sentinel lymph nodes to which cancer might first spread. Pathologists can then perform a more intensive analysis of the few sentinel nodes instead of sorting though the 10-25 nodes removed with a standard dissection.

If the sentinel lymph nodes are found to be free of cancer, there is no need to perform a traditional complete axillary lymph node dissection. This is advantageous because the side effects of a complete dissection, such as lymphedema (swelling caused by excess fluid build-up), numbness, burning, infection and stiffness can be minimized or avoided completely.

“The sentinel lymph node biopsy came about because surgeons were looking for a less-invasive technique to accomplish the same thing that the full axillary node dissection was accomplishing – but with fewer side effects,” Dr. Aanestad said.

Minimally invasive procedure

The procedure begins when the patient is injected with a small amount of radioactive tracer and a blue dye around the breast cancer.

These substances are absorbed by the lymph system and help the doctor identify the sentinel lymph node(s) – which will be blue and emit a small amount of radiation. A special device called a gamma probe is used to pick up the radioactive signal.

The surgeon makes a small incision and removes the sentinel node (or nodes). A pathologist then examines them under a microscope. If cancer cells are not seen, it is unlikely that the cancer has spread to the other lymph nodes and there is no need to remove them.

All the lymph nodes in the area are removed, however, if cancer is present in the sentinel lymph node. The lymph nodes may also be taken out if the sentinel lymph node cannot be located.

The sentinel lymph node biopsy can be done in combination with a lumpectomy, a mastectomy or as a separate procedure. When done as a separate procedure, the entire biopsy, including the time it takes for the radioactive tracer to be absorbed prior to surgery, takes about three hours. Sentinel lymph node biopsy may be performed on an outpatient basis. But, when done with cancer-removal surgery, a hospital stay may be required.

“Sentinel lymph node biopsy is a minimally invasive approach with fewer side effects and faster recovery times. It is highly effective in helping us determine whether or not cancer has affected the regional lymph nodes. That’s why it has become a much sought after procedure for women with breast cancer.”

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