Sentinel Lymph Node Biopsy

Test Overview

A sentinel lymph node biopsy removes lymph node tissue to see if a known cancer has spread. This biopsy may be done instead of a bigger surgery called lymph node dissection.

The sentinel lymph node is the first node where cancer cells may move to after they have left the original cancer site and started to spread. For example, the sentinel node (SN) for breast cancer is normally one of the lymph nodes under the arm.

Your doctor injects a blue dye or radioactive tracer or both into the area around the original cancer site. The dye or tracer moves to the sentinel node that is close to the cancer site. Your doctor can see the dye or tracer with a special device. The lymph node can be taken out and looked at under a microscope at the time of the biopsy. If a sentinel node is positive for cancer cells, more surgery may be needed to remove more lymph nodes.

Other tests, such as a culture, genetic tests, or immunological tests, may be done on the lymph node sample.

Why It Is Done

A sentinel lymph node biopsy is done to:

• See if a known cancer, such as breast cancer or melanoma, has spread to the lymph nodes.
• Remove a few lymph nodes instead of removing all the lymph nodes in an area. If the sentinel lymph node does not have cancer, this biopsy takes less time, is simpler to do, and has a lower chance of long-term problems, such as ongoing swelling of an arm or leg (lymphedema).

How To Prepare

• Follow the instructions exactly about when to stop eating and drinking. If you don't, your biopsy may be canceled. If your doctor told you to take your medicines on the day of the test, take them with only a sip of water.
• Understand exactly what surgery is planned, along with the risks, benefits, and other options.
• Tell your doctor ALL the medicines, vitamins, supplements, and herbal remedies you take. Some may increase the risk of problems during your test. Your doctor will tell you if you should stop taking any of them before the test and how soon to do it.
• If you take aspirin or some other blood thinner, ask your doctor if you should stop taking it before your surgery. Make sure that you understand exactly what your doctor wants you to do. These medicines increase the risk of bleeding.
• Make sure your doctor and the hospital have a copy of your advance directive. If you don’t have one, you may want to prepare one. It lets others know your health care wishes. It’s a good thing to have before any type of surgery or procedure.
• Be sure you have someone to take you home. Anesthesia and pain medicine will make it unsafe for you to drive or get home on your own.

How It Is Done

• Your doctor injects a dye, a radioactive tracer, or both into your body near your cancer site. The dye stains the sentinel lymph node or nodes so they can be seen. The tracer travels to the sentinel lymph node where it can be detected.
• Your doctor removes the sentinel node or nodes. The node is looked at under a microscope for cancer cells. The results help your doctor decide whether to remove any more nodes.
• You will have some stitches and a bandage over the biopsy site.

How long the test takes

• The biopsy usually takes 30 to 60 minutes. It may take longer if you have surgery to remove the cancer at the same time.

How It Feels

You will feel only a quick sting from the needle if you have a local anesthesia to numb the biopsy area. If you have a core needle biopsy, you may feel some pressure when the biopsy needle is put in.

You may have general anesthesia if your lymph node is deeper in the body or the biopsy is part of a larger surgery. If so, you won't feel your biopsy at all.

Risks

It is possible to have some problems after a biopsy. Your doctor will give you instructions on what to do if a problem occurs. Risks include:

• Bleeding from the biopsy site. This risk is higher for people who have bleeding problems or who take blood-thinning medicines. If you are at risk for bleeding, you may be given blood clotting factors before the biopsy.
• Skin numbness at the biopsy site.
• Infection at the biopsy site.
• Swelling and fluid buildup (lymphedema). This is less likely after a sentinel node biopsy than if more lymph nodes are taken out (dissection).
• Problems from general anesthesia, if it is used.
• Damage to nerves at the biopsy site. This may cause weakness or pain.

Results

Results are usually available within a few days.

The lymph node tissue is usually treated with special dyes (stains) that color the cells so problems can be clearly seen.

Normal

• The dye or tracer flows evenly to the sentinel lymph node.
• The lymph node has normal numbers of lymph node cells.
• The structure of the lymph node and the cells look normal.
• No cancer is present.

Abnormal

• The dye or tracer does not flow evenly to the sentinel lymph node.
• The sentinel lymph node cannot be identified.
• Cancer cells may be seen. Cancer cells may start in the lymph nodes, such as in Hodgkin lymphoma. Cancer cells may have spread, or metastasized, from other sites, such as in breast cancer or melanoma.

If the sentinel lymph node does not have cancer, no other nodes will need to be taken out.

If the sentinel lymph node contains cancer cells, more nodes may need to be removed.