Why Examine the Lymph Nodes?

Whether you’ve had a mastectomy or a lumpectomy for invasive cancer, you may also have a procedure called axillary lymph node dissection: some of the lymph nodes from your armpit will be removed and examined for evidence of cancer spread. This information is extremely important for deciding whether you will need additional therapy.

What exactly are lymph nodes? Arteries and veins carry blood to and from various parts of the body. Some fluid seeps out of these blood vessels, and is returned to the blood stream by a network of thin tubes called lymphatic ducts. This fluid, called lymph, helps the body wash away foreign particles or other debris that can collect in the spaces between cells.

Lymphatic ducts from both the breast and the arm come together in the axilla, or armpit. There, the lymph is filtered through tiny bean-shaped organs called lymph nodes. Foreign particles (such as bacteria from an infection in the finger, or break-away cancer cells from a tumor in the breast) are trapped in the lymph nodes before they can enter the general circulation.

Until a few years ago, the only way to check the lymph nodes for evidence of cancer spread was to perform an axillary lymph node examination, which consists of removing a portion of the fat pad from the armpit, with ten to twenty imbedded lymph nodes. This specimen is submitted to a pathologist, who slices each node and examines it under the microscope for presence of cancer cells. The report is sent to the surgeon three to ten days after surgery


“Lymph nodes help me predict whether the cancer has spread.”

Sentinel Lymph Node Biopsy

There is an important new surgical technique for lymph node examination, called sentinel lymph node biopsy. In many communities, it is considered the “standard of care”.

The principle is simple. As lymphatic fluid drains away from the breast, it first passes through certain lymph nodes located in key parts of the drainage system. These are called sentinel nodes, because they act as gatekeepers. If the sentinel node is free of cancer cells, the odds are that there will be no cancer in the nodes located downstream. If cancer is found, a full dissection is done.

The procedure begins with the injection of a blue dye and/or of a small amount of radioactive material into the area near the tumor. The lymphatic fluid carries the dye to the first node in its path—the sentinel node. During surgery, the node is identified, removed and examined. If no cancer cells are found, a full dissection can be avoided.

A sentinel lymph node biopsy takes longer, and requires a surgeon who is experienced in the technique, but it helps avoid several potentially serious complications that can result from a full axillary lymph node dissection.

After Axillary Lymph Node Dissection

One complication of extensive surgery in the armpit is damage to one or more of the nerves, either accidentally or because the injury was unavoidable. This may result in long term numbness in the armpit area, or weakness in some of the shoulder muscles. Often the numbness will improve over several years, but the sensitivity will never be normal. The weakness can generally be overcome with time.



A more serious problem is a condition called lymphedema. It is caused by scarring of lymph vessels in the underarm area after removal of the lymph nodes and their connecting ducts. The circulation of lymph fluid is slowed, causing swelling of the arm, limiting its function, and making the arm more prone to infection.

As many as 10-20% of women undergoing axillary lymph node dissection will develop lymphedema of the arm. The condition may occur soon after surgery, or years later. In most cases it will be mild – you will notice some swelling in your fingers that may affect how you wear your rings. In women who are older, who are overweight, or who had radiation therapy, lymphedema is more likely to be more severe.

There are several precautions that you must take to help you prevent it. These include avoiding over-using the arm, and protecting it from skin infections and injuries.

For women who develop lymphedema, the treatment will focus on lymph-draining massage, special compression bandages, and special exercises, all under the supervision of a qualified therapist.