Procedure

Lymph Node Biopsy- Cancer/Oncology, Ear Nose And Throat (ENT), Gastroenterology, General Surgery

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Sentinel Lymph Node Biopsy was originally published by the National Cancer Institute.

Lymph Node Biopsy

A procedure in which all or part of a lymph node is removed and checked under a microscope for signs of infection or disease, such as cancer.

What are lymph nodes?

Lymph nodes are small round organs that are part of the body’s lymphatic system. They are found widely throughout the body and are connected to one another by lymph vessels. Groups of lymph nodes are located in the neck, underarms, chest, abdomen, and groin. A clear fluid called lymph flows through lymph vessels and lymph nodes.

Lymph originates from a fluid, known as interstitial fluid, that has diffused, or “leaked,” out of small blood vessels called capillaries. This fluid contains many substances, including blood plasma, proteins, glucose, and oxygen. It bathes most of the body’s cells, providing them with the oxygen and nutrients they need for growth and survival. Interstitial fluid also picks up waste products from cells as well as other materials, such as bacteria and viruses, to help remove them from the body’s tissues. Interstitial fluid eventually collects in lymph vessels, where it becomes known as lymph. Lymph flows through the body’s lymph vessels to reach two large ducts at the base of the neck, where it is emptied into the bloodstream.

Lymph nodes are important parts of the body’s immune system. They contain B lymphocytes, T lymphocytes, and other types of immune system cells. These cells monitor lymph for the presence of “foreign” substances, such as bacteria and viruses. If a foreign substance is detected, some of the cells will become activated and an immune response will be triggered.

Lymph nodes are also important in helping to determine whether cancer cells have developed the ability to spread to other parts of the body. Many types of cancer spread through the lymphatic system, and one of the earliest sites of spread for these cancers is nearby lymph nodes.

What is a sentinel lymph node?

A sentinel lymph node is defined as the first lymph node to which cancer cells are most likely to spread from a primary tumor. Sometimes, there can be more than one sentinel lymph node.

What is a sentinel lymph node biopsy?

A sentinel lymph node biopsy (SLNB) is a procedure in which the sentinel lymph node is identified, removed, and examined to determine whether cancer cells are present.

A negative SLNB result suggests that cancer has not developed the ability to spread to nearby lymph nodes or other organs. A positive SLNB result indicates that cancer is present in the sentinel lymph node and may be present in other nearby lymph nodes (called regional lymph nodes) and, possibly, other organs. This information can help a doctor determine the stage of the cancer (extent of the disease within the body) and develop an appropriate treatment plan.

What happens during an SLNB?

A surgeon injects a radioactive substance, a blue dye, or both near the tumor to locate the position of the sentinel lymph node. The surgeon then uses a device that detects radioactivity to find the sentinel node or looks for lymph nodes that are stained with the blue dye. Once the sentinel lymph node is located, the surgeon makes a small incision (about 1/2 inch) in the overlying skin and removes the node.

The sentinel node is then checked for the presence of cancer cells by a pathologist. If cancer is found, the surgeon may remove additional lymph nodes, either during the same biopsy procedure or during a follow-up surgical procedure. SLNBs may be done on an outpatient basis or may require a short stay in the hospital.

SLNB is usually done at the same time the primary tumor is removed. However, the procedure can also be done either before or after removal of the tumor.

What are the benefits of SLNB?

In addition to helping doctors stage cancers and estimate the risk that tumor cells have developed the ability to spread to other parts of the body, SLNB may help some patients avoid more extensive lymph node surgery. Removing additional nearby lymph nodes to look for cancer cells may not be necessary if the sentinel node is negative for cancer. All lymph node surgery can have adverse effects, and some of these effects may be reduced or avoided if fewer lymph nodes are removed. The potential adverse effects of lymph node surgery include the following:

  • Lymphedema, or tissue swelling. During SLNB or more extensive lymph node surgery, lymph vessels leading to and from the sentinel node or group of nodes are cut, thereby disrupting the normal flow of lymph through the affected area. This disruption may lead to an abnormal buildup of lymph fluid. In addition to swelling, patients with lymphedema may experience pain or discomfort in the affected area, and the overlying skin may become thickened or hard. In the case of extensive lymph node surgery in an armpit or groin, the swelling may affect an entire arm or leg. In addition, there is an increased risk of infection in the affected area or limb. Very rarely, chronic lymphedema due to extensive lymph node removal may cause a cancer of the lymphatic vessels called lymphangiosarcoma.
  • Seroma, or the buildup of lymph fluid at the site of the surgery.
  • Numbness, tingling, or pain at the site of the surgery.
  • Difficulty moving the affected body part.

Is SLNB associated with other harms?

SLNB, like other surgical procedures, can cause short-term pain, swelling, and bruising at the surgical site and increase the risk of infection. In addition, some patients may have skin or allergic reactions to the blue dye used in SLNB. Another potential harm is a false-negative biopsy result—that is, cancer cells are not seen in the sentinel lymph node although they are present and may have already spread to other regional lymph nodes or other parts of the body. A false-negative biopsy result gives the patient and the doctor a false sense of security about the extent of cancer in the patient’s body.

Is SLNB used to help stage all types of cancer?

No. SLNB is most commonly used to help stage breast cancer and melanoma. However, it is being studied with other cancer types, including colorectal cancer, gastric cancer, esophageal cancer, head and neck cancer, thyroid cancer, and non-small cell lung cancer (1).

Selected References

  1. Chen SL, Iddings DM, Scheri RP, Bilchik AJ. Lymphatic mapping and sentinel node analysis: current concepts and applications. CA: A Cancer Journal for Clinicians 2006; 56(5):292–309. [PubMed Abstract]
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