The Abramson Cancer Center of the University of Pennsylvania
Last Modified: January 22, 2002
This "Helpful Facts" sheet is designed to give you basic information on sentinel lymph node biopsy. More detailed information can be provided by your doctor or nurse. If, you have other questions or would like additional information, please talk to your doctor or nurse.
What is the Lymph System?
The lymph system is important in your body's defense against infection. It is made up of lymph vessels and lymph nodes. The lymph vessels collect fluid and protein from surrounding body tissues. This fluid then goes through the lymph nodes, which act to filter out and trap bacteria, viruses, cancer cells, and other unwanted substances. Lymph nodes can be found clustered in various parts of the body, including the neck, axilla (underarm area) and groin.
What is a Sentinel Lymph Node Biopsy?
The sentinel lymph node biopsy is an alternative to the axillary lymph node dissection when all of the lymph nodes are removed. The sentinel lymph node is the first node or nodes that are "standing guard" for your breast. If cancer cells are breaking away from the tumor and traveling through the lymph system, the sentinel node(s) are the first lymph nodes to which cancer cells would spread. In a sentinel node biopsy for breast cancer, your surgeon looks under the arm (axilla) for the first lymph node(s) that drain the breast. Only those lymph nodes identified as sentinel lymph nodes are removed. If the sentinel node(s) do not have cancer, chances are the other nodes in the axilla have not been affected and can be left alone. If the sentinel lymph node biopsy is positive, however, spread to other lymph nodes is possible and a full axillary dissection would be recommended.
How is a Sentinel Lymph Node Biopsy Performed?
On the morning of surgery, you will go to Radiology where the mammographers will give you an injection of a small amount of radioisotope dye (a low-level radioactive substance) around the tumor. Ultrasound will be used to guide the injection. You will then go to Nuclear Medicine where a lymph node scan will be done. This scan traces the flow of the radioisotope through the lymph system to find the approximate location of the sentinel node(s). This part of the procedure takes 60 to 90 minutes.
You will then be taken to the operating room where the surgeon injects a blue dye into the tumor area or under the nipple. The blue dye then flows through the lymph system into the sentinel lymph node(s), coloring them blue. The surgeon has a small device, called a gamma probe, that can be used like a geiger counter to look at the activity of radioisotope in the various lymph nodes that drain the breast. This probe helps the surgeon find the location of the sentinel lymph node(s). Through a small incision under the arm, the surgeon identifies any lymph nodes that are blue or that have the radioactive dye, and these lymph nodes are removed. The number of sentinel lymph nodes vary but in general, one to four lymph nodes are removed. The pathologist then analyzes the lymph nodes under the microscope. The results are usually available in seven to ten days
NOTE: Remember that the radioisotope dye and lymph node scan does not tell you that the cancer has spread. They only mark the first node(s) that the cancer cells might have spread to so that the surgeon can remove them to be tested. Only the pathologist, by looking under the microscope, can tell whether cancer cells have spread to the lymph nodes.
What are the Risks of a Sentinel Lymph Node Biopsy?
As with any surgery there is a risk of bleeding, infection and poor wound healing. Fluid or blood could accumulate and require drainage. A small percentage of patients, less than 1%, may have an allergic reaction to the blue dye. There will be some blue staining in the breast skin for a few weeks up to two months. You will also have blue urine for a few days, which is normal.
How Will I Look and Feel After the Sentinel Lymph Node Biopsy?
You will have a small scar under your arm. Initially there will be some swelling and discomfort.
How Long Will I Be in the Hospital?
You will be discharged from the Ambulatory Procedure Unit on the same day. Following surgery, you will be in the recovery room until your discharge. You will need to be picked up by a responsible adult at the time of discharge. Please inform family members that this process will take most of the day.