One of the pieces of information needed by your doctor, so that he or she can “stage” a breast cancer, is whether or not the cancer has spread to the lymph nodes, or glands, underneath the arm.

Those lymph nodes are a component of your body’s lymphatic system, which helps your body fight infection as well as removing toxins and debris. The lymphatic channels are the system’s “streams” and “rivers” that drain into the lymph nodes, or its “lake.” Cancer cells from a breast cancer can break off and travel through the lymphatic channels into lymph nodes.

Axillary Node Dissection

Surgeons have used a procedure called an axillary lymph node dissection to determine if the cancer had spread to the lymph nodes. In this procedure, a surgeon removes the lymph node tissue within a triangle that is bordered by the axillary vein (the vein that drains the blood from the arm to the heart), the chest wall, and the large muscle going to the back, called the latissimus dorsi, sparing the nerves that cause muscle movement.

An axillary lymph node dissection typically removes 10 to 20 lymph nodes (or more) for evaluation. It provides very accurate staging and treatment for breast cancer; however, it may also cause long-term pain and swelling of the arm and/or breast, known as lymphedema. Because of this possible side effect, a more limited removal of lymph nodes known as sentinel lymph node biopsy was developed and adopted in the 1990s (see below). Some situations still require axillary node dissection, such as when multiple abnormal nodes can be felt or when nodes have not gone away following treatment administered before surgery, or in cases of inflammatory or recurrent breast cancer.

Sentinel Lymph Node Biopsy

The efforts of breast surgeons and the positive results of clinical trials led to the development and adoption of another procedure, known as sentinel lymph node biopsy.

The sentinel lymph node (or nodes) is/ are the first lymph node(s) to which a breast cancer will travel as it spreads. Therefore, the principle of sentinel lymph node biopsy is that if there is no cancer in the sentinel lymph node(s), then there should be no cancer in other lymph nodes “downstream” from the sentinel lymph node.

During the procedure, a surgeon will first use one of the following techniques to locate the sentinel lymph nodes:

• Place radioactive material into the breast through an injection into the breast. The radioactive material will then collect into the sentinel lymph node, which may be located by use of a Geiger counter.
• Inject a blue dye into the breast. The blue dye will collect into the sentinel lymph nodes, which can be identified.
• Use both a radioactive dye and a blue dye to find the sentinel lymph nodes.

Then the surgeon will remove the sentinel lymph nodes through an incision underneath the arm. Once they are removed, the nodes are sent to a pathologist who will look at them underneath a microscope to see if they contain cancer.

Determining whether the axillary lymph nodes contain cancer will help your doctor determine what additional breast cancer therapy, such as chemotherapy and radiation therapy, is needed to treat the breast cancer.

The American Society of Breast Surgeons’ Consensus Statement

Performance and Practice Guidelines for Sentinel Lymph Node Biopsy in Breast Cancer Patients (503.7KB)