Axillary lymph node dissection is a surgical procedure which is performed to remove lymph nodes in the underarm area. Lymph nodes present in the armpit are known as axillary lymph nodes. An axillary lymph node dissection is also referred to as axillary node dissection or axillary dissection.

Lymph nodes are bean-shaped structures that act as a filtering mechanism for the lymphatic system, which is composed of vessels that gather fluids from tissues, filter them, and direct them back to blood. The lymphatic system helps the body to fight infection.

Axillary Dissection and Cancer

Axillary dissection is a standard procedure for the staging and management of the axilla in breast cancer patients. Patients in the early stages of breast carcinoma have a 30-40% chance of having positive axillary nodes or nodes that test positive for cancer cells.

German surgeon, Lorenz Heister was the first to use axillary node dissection in breast cancer treatment in the 18th century. Trials conducted as part of the National Surgical Adjuvant Breast Project B-04 found that axillary node dissection does not affect survival rates in patients. Many studies proved that axillary dissection helps in controlling the disease locally, thus improving overall survival. The local recurrence rate after axillary dissection was found to be less than of 2%.

Thus, the staging of the axilla is a key step in the treatment of breast cancer. The status of axillary node is an important prognostic variable in affected individuals with early stage breast cancer. The number of nodes with cancer metastasis also has significant prognostic value.

Levels of Axillary Nodes

The axillary nodes are classified into 3 levels:

• Level I is called the low axilla and is located in the lower portion of the armpit
• Level II is called mid axilla and is present in the middle section of the armpit
• Level III is known as high axilla and is present near the breastbone in the upper portion of the armpit

If the cancer has spread to any of these 3 axillary nodes, then the doctor will recommend an axillary dissection. The number of nodes varies from one woman to another; so the decision is largely based on the location of the cancer and not the number of nodes.

Based on the three levels of axillary nodes, there are three options for axillary dissection:

• Level I – This procedure involves incision of all tissue under the axillary vein and those at the sides where the vein meets the tendon of the latissimus dorsi muscle
• Level II – This level of dissection removes affected tissues in the middle part of the pectoralis minor muscle
• Level III – This level involves the most aggressive dissection of the three and removes all the lymph nodes from the axilla

Traditionally, in a majority of cases, level I or II nodes are surgically removed if the sentinel node is positive for cancer cells or if there is a cancerous node in the armpit. In women having invasive breast cancer, axillary dissection usually accompanies a mastectomy. The surgeon usually removes 5 to 30 nodes, depending on the results of physical exam and other tests that reveal the extent of spread of cancer cells in the lymph nodes.

Benefits of Axillary Dissection

An axillary node dissection can help physicians in the following:

• Determine the number of nodes affected and extent of spreading of cancer to the lymph nodes
• Remove lymph nodes that have a high chance of becoming cancerous and nodes that test positive for cancer cells
• Remove cancer cells that persist after chemo or radiation therapy
• Reduce the recurrence of cancer
• Help physicians decide on further treatment

References

• http://emedicine.medscape.com/article/1894763-overview
• http://www.cancer.ca/en/cancer-information/diagnosis-and-treatment/tests-and-procedures/axillary-lymph-node-dissection/?region=on
• http://www.breastcancer.org/treatment/surgery/lymph_node_removal/axillary_dissection
• http://www.hopkinsmedicine.org/breast_center/treatments_services/breast_surgical_oncology/axillary_node_dissection.html