Key Terms: Computed tomography (CT or CAT) scan, Magnetic resonance imaging, Malignant.
Definition
Lymph node dissection (lymphadenectomy) is the surgical removal of lymph nodes in order to assess the spread of cancer.
Purpose
The lymph system is the body's primary defense against infection. It consists of the spleen, tonsils, thymus, lymph nodes, lymph vessels, and the clear, slightly yellow fluid called lymph. These components produce and transport cells and proteins that help rid the body of infection.
The lymph vessels are similar to veins, only instead of carrying blood as veins do, they circulate lymph to tissues in the body. There are about 600 small, bean-shaped collections of tissue found along the lymph vessels. These are called lymph nodes. They produce cells and proteins that fight infection. They also clean and filter foreign cells, such as bacteria or cancer cells, out of the lymph.
Cancer cells can break off from the original tumor and metastasize (spread) through the lymph system to distant parts of the body, where secondary tumors are formed. The purpose of a lymph node dissection is to remove the lymph nodes that have trapped cancer cells so that the extent of spread can be determined. Lymph node dissection is done for many different types of cancers, including cancers of the head and neck, breast, prostate, testes, bladder, colon, and lung.
About 200 lymph nodes are in the head and neck and another 30 to 50 are in the armpit. More are located in the groin area. Lymph nodes are sometimes called lymph glands, although they are not true glands. When someone talks about having swollen glands, they are referring to swollen lymph nodes.
Normally lymph nodes are no larger than 0.5 in (1.3 cm) in diameter and are difficult to feel. However, when lymph nodes trap bacteria or cancer cells, they can increase in size to greater than 2.5 in (6 cm). Most often, hot and painful swollen nodes are caused by trapped bacteria. Swollen lymph nodes caused by cancer are usually painless.
Precautions
This operation usually will not be performed if the cancer has already metastasized to another site. In this case, removing the lymph nodes will not effectively contain the cancer. As with any surgery, women who are pregnant should inform their doctors before a lymph node dissection.
Description
Lymph node dissection is usually done by a surgeon in a hospital setting, under general anesthesia. An incision is made and tissue is pulled back to reveal the lymph nodes. The surgeon is guided in what to remove by the location of the original cancer. Sample lymph nodes may be sent to the laboratory for examination. If the excised nodes do contain malignant cells, this would indicate that the cancer has spread beyond the original site, and recommendations can then be made regarding further therapy.
Preparation
Tests may be done before the operation to determine the location of the cancer and which nodes should be removed. These tests may include lymph node biopsies, CT (computed tomography) scans, and MRI scans. In addition, standard pre-operative blood and liver function tests are performed. The patient will meet with an anesthesiologist before the operation, and should notify the anesthesiologist about all drug allergies and all medication (prescription, non-prescription, or herbal) that he or she is taking.
Aftercare
How long a person stays in the hospital after lymph node dissection depends on how many lymph nodes were removed, their location, and whether surgery to remove the primary tumor or other structures was performed at the same time. Drains are inserted under the skin to remove the fluid that accumulates after the lymph nodes have been removed, and patients are usually able to return home with the drains still in place. Some patients are able to leave the same day or the day following the procedure.
An accumulation of lymph fluid that causes swelling, a condition known as lymphedema, is the most feared side effect of lymph node dissection. If swelling occurs, patients should consult their doctors immediately. Swelling may indicate that a new tumor is blocking a lymph vessel, or that a side effect of lymph node dissection is present. Treatment for lymphedema in people with cancer is different than treatment of lymphedema that arises from other causes. In cancer patients, it is essential to alleviate swelling without spreading cancer cells to other parts of the body, therefore an oncologist (cancer specialist) should be consulted before beginning any treatment.
Risks
People who have lymph nodes removed are at increased risk of developing lymphedema, which can occur in any part of the body where lymph accumulates in abnormal quantities. When the amount of fluid exceeds the capacity of the lymph system to move it through the body, it leaks into the tissues and causes them to swell. Removing lymph nodes and lymph vessels through lymph node dissection increases the likelihood that the capacity of the lymph transport system will be exceeded.
Lymphedema can occur days or weeks after lymph node dissection. Radiation therapy also increases the chance of developing lymphedema, so those people who have radiation therapy following lymph node dissection are at greatest risk of experiencing this side effect. Lymphedema slows healing, causes skin and tissue damage, and when left untreated can result in the development of hard or fibrous tissue. People with lymphedema are also at risk for repeated infection, because pools of lymph in the tissues provide a perfect spot for bacteria to grow. In severe cases, untreated lymphedema can develop into a rare form of cancer called lymphangiosarcoma.
Other risks associated with lymph node dissection are the same as for all major surgery: potential bleeding, infection, and allergic reaction to anesthesia.
Normal Results
Normal lymph nodes are small and flat and show no cancerous cells under the microscope.
Questions to Ask the Doctor
- How will you determine which lymph nodes should be removed?
- How should I prepare for this procedure?
- Are there precautions I can take to help prevent lymphedema?
- How will lymph node dissection affect my daily life?
- Will you be removing anything else besides lymph nodes during this operation?
- About how long will I have to stay in the hospital?
- Will having my lymph nodes removed increase my chances of getting infections?
Abnormal Results
Abnormal lymph nodes are enlarged and show malignant cells when examined under the microscope.
Resources
Organizations
American Cancer Society, National Headquarters. 1599 Clifton Rd. NE, Atlanta, GA 30329. 800(ACS)-2345.
Cancer Information Service. National Cancer Institute. Building 31, Room 10A19, 9000 Rockville Pike, Bethesda, MD 20892. (800) 4-CANCER.
National Lymphedema Network. Latham Square, 1611 Telegraph Ave., Suite 1111, Oakland, CA 94612-2138. (800) 541-3259.
—Tish Davidson, A.M.
