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 Dr. Ball determine the stage of the cancer, the extent of the disease within the body, and develop an appropriate treatment plan.

What happens during an SLNB?

Dr. William A. Ball, Jr., 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 cancer specialists or physicians 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.

Click HERE to see an animation of a Breast Lumpectomy and Sentinel Lymph Node Biopsy.