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Sentinel Node Biopsy

By: Alison Estabrook, MD
By: Paul Tarttar, MD
By: Howard Mizrachi, MD
The traditional way to take care of breast cancer that may have spread to the armpit (axilla) is to perform a mastectomy with axillary node dissection. Axillary node dissection involves removing all of the lymph nodes in the axilla that may be involved with cancer.
Sentinel node biopsy is a less invasive way of detecting cancer in the lymph nodes, which under special circumstances described below, may prevent their complete removal.

The paragraphs below describe all of the issues involved in performing surgery for breast cancer and what role sentinel node biopsy plays.

What are lymph nodes?
Lymph nodes are tiny structures, each about the size of a small pea, located throughout the body. They contain many immunological "fighter cells" that act as filters to protect the body against attack. Fluids and cells from organs of the body pass through the lymph nodes. Cancer cells from the breast pass to the lymph nodes in the axilla. There are over 50 small lymph nodes in the axilla. In the case of a cancer biopsy, at least 5 to 10 nodes are removed surgically and examined under the microscope for cancer by pathologists.


Why do axillary lymph nodes need to be removed?
The reason lymph nodes are removed is so that they can be studied under the microscope. If there are no cancer cells in the lymph nodes, then the risk of recurrence of breast cancer is much lower than if cancer cells are found. This is important because if no cancer is found in the lymph nodes, then less aggressive treatment is required to control the breast cancer. Patients with breast cancer cells in their lymph nodes will require additional treatment (more extensive surgery, and/or chemotherapy) and may carry a higher rate of recurrence. Lymph node removal also allows as much of the cancer as possible to be removed. This may be important before starting any additional treatment with radiation or chemotherapy.

What is axillary node dissection?
Axillary node dissection is part of the conventional surgical management of breast cancer. It is commonly performed as part of lumpectomy or mastectomy, and is responsible for most postoperative complaints.

Complications of axillary node dissection include paresthesias (costobrachial nerve injury), wound infection, seroma, drain complications, and acute and chronic lymphedema. Complete dissection involves surgically removing all axillary lymph nodes (in levels I, II, III). Forty percent of patients develop acute lymphedema and five to ten percent develop chronic lymphedema. Lymphedema has no effective treatment.

Axillary node dissection may be the best procedure for patients at risk for larger tumors and higher risk for metastases because node involvement is the most important independent variable for predicting outcome from breast cancer. Knowing the extent of nodal involvement is important for the staging of breast cancer and directing treatment. Small axillary node metastases may be cured by surgical removal, chemotherapy, or radiation.
What is a sentinel node biopsy?
The sentinel node is the first lymph node that is drained by the breast. It can be identified by injecting a dye or radioisotope into the breast and looking for the dye or radioisotope in a lymph node in the underarm. Using both dye and radioisotope seems to give the best results.

It is thought that because the sentinel node is the first draining lymph node, it should be a good indicator of the status of the entire axilla. If the sentinel node is free of cancer, then the other lymph nodes in the axilla should be clean also, eliminating the need for further surgery.

Why is sentinel node biopsy used?
Choices about treatment of breast cancer, and its subsequent outcome, depend on whether the cancer has spread to other areas of the body. Typically, breast cancer first spreads to the underarm (axilla) lymph nodes. In fact, spread to the axillary lymph nodes is one of the strongest predictors of outcome for breast cancer and it determines whether chemotherapy is needed. Removing axillary lymph nodes to look for presence of cancer has traditionally been part of breast surgery. While it is an accurate way to detect spread of breast cancer, it often leaves a woman without adequate drainage of her arm, resulting in uncomfortable swelling as well as loss of normal sensation in the arm (the sensory nerves are cut in the procedure). Sentinel node biopsy was developed to accurately assess the spread of breast cancer without risking arm-swelling and loss of sensation.


How is the sentinel node biopsy performed?
There are several methods used to identify the sentinel node.

One method involves injecting a radioisotope (technetium-99) into the breast tissue or skin adjacent to the tumor several hours before surgery. The radioisotope reaches the lymphatic channels in the breast and travels to the main lymph node (sentinel node) over one to six hours. The location of this node can then be detected using a Geiger Counter.

Another method is to inject blue dye (isosulfan blue dye) adjacent to the breast tumor just prior to surgery. The blue dye is also taken up by the lymphatics and within 15 minutes it can be seen in the sentinel node.
A third method is to use a combination of the radioactive and dye techniques. The sentinel node biopsy can be performed with local anesthetic and sedation. An incision is made in the underarm at the site identified with the gamma detection probe or Geiger Counter. Sentinel node radioactivity is measured against a background count in the surrounding breast tissue. The lymph node or nodes that are colored blue from the dye and respond to the Geiger Counter are then removed (biopsied) for examination for tumor. Eighty percent of the time there is concordance between the node that is radioactive and also blue. Twenty percent of the time, the radioactive node is not blue and in that case both the radioactive node and the blue node are removed. If no further breast surgery is needed, then the wound is closed, covered with a waterproof dressing and the patient goes to recovery.
What kind of anesthesia is used for sentinel node biopsy?
Monitored anesthesia care (MAC), using sedating medications together with local anesthetics at the operative site, is usually all that is necessary for this procedure. You can remain comfortable and relaxed during the procedure without having to undergo general anesthesia. Side effects are minimal, but can include sleepiness, nausea, vomiting, and incisional pain and discomfort. This procedure is commonly performed on an outpatient basis and you should be ready to go home within a couple of hours after the procedure is finished.

If sentinel node biopsy is performed as part of a lumpectomy or mastectomy, then general anesthesia is commonly used to prevent pain, discomfort and awareness. Side effects after the surgery can include nausea, vomiting, sleepiness, incisional pain, and discomfort. These side effects should dissipate over the next several days. A small lumpectomy can sometimes be accomplished with MAC and local anesthesia. If the area is large, local anesthetics plus sedation may not be enough to make you comfortable.

If there is no need for further breast surgery after the sentinel node biopsy (lumpectomy or mastectomy), then the patient can go straight to a recovery room and then home. This type of procedure is usually performed on an outpatient basis. Patients can bathe or shower normally since the dressings are waterproof and there are no drains to hinder movement.


What role does the pathologist play?
The sentinel node is carefully examined by a pathologist for evidence of breast cancer cells. The testing methods are extremely sensitive. Multiple sections of the node are stained with an antibody that attaches to a protein (called cytokeratin) found in breast cancer cells. This special stain greatly increases the chance that if even a single cancer cell exists, it will be identified. Pathologists use techniques that allow for the detection of small tumor volumes and accurate cancer staging.
Sentinel node biopsy requires a multidisciplinary approach to patient care. Surgeons, radiologists, pathologists, and nuclear medicine physicians all work together.
What are suitable conditions for sentinel node biopsy?
Sentinel node biopsy is most commonly used in patients with small invasive breast cancers who are at low risk for axillary node spread (metastases). The standard of care for patients with metastatic breast cancer is complete removal of the cancer (mastectomy or lumpectomy) and a complete axillary node dissection. If it is already known that the breast cancer has spread to lymph nodes and/or other parts of their body, then traditional axillary node dissection may be more appropriate.

Because of the high degree of sensitivity in detecting cancer in the lymph nodes, sentinel node biopsy is useful for patients who have noninvasive ductal carcinoma in situ.

Patients who have breast tumors located near the armpit, previous surgery or injury that involves the armpit (previous breast reduction surgery, implant surgery, burns), or lymphatic drainage problems may not be suitable for sentinel node biopsy.


What are the benefits of sentinel node biopsy?
Sentinel Node biopsy may reduce the ...
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mom23kidz1

Thanx for the Info