Sentinel Lymph Node Biopsy

Why this test may be ordered

• To find out whether an early-stage cancer has spread through your lymphatic system to your lymph nodes or other parts of your body
• Most often used for people who have breast cancer or melanoma
• Usually done when the tumor is being removed
• Helps your provider create the best treatment plan for you

Preparation and collection

You will probably need to fast (not eat or drink) for several hours before the test. You may also need to stop taking blood thinners, such as aspirin, for a certain time before your test. Your provider will let you know when you need to stop taking your medicine and anything else to do to prepare for the test. In addition, be sure to arrange for someone to take you home. You may be groggy and confused after you wake up from the procedure.

A sentinel lymph node biopsy may be done in a hospital or an outpatient surgical center. The procedure usually includes a special type of imaging test called lymphoscintigraphy. The steps include: numbing the skin, injecting a radioactive tracer near the tumor, possibly injecting a blue dye, giving general anesthesia, taking images to locate the sentinel node, and then removing the node and sending it to a lab to be checked for cancer cells. The original tumor is also usually removed during the procedure.

You may have a little bleeding, pain, or bruising at the biopsy site. There is also a small risk of infection, which can be treated with antibiotics. Allergic reactions to the tracer are rare and usually mild. If only the sentinel lymph node is removed, there is a low risk of lymphedema (swelling, usually of the arms or legs) from the lymph fluid. The risk increases with the number of lymph nodes removed. There is very little exposure to radiation in a sentinel lymph node biopsy. While radiation exposure from the tracer in a sentinel lymph node biopsy is safe for most adults, it can be harmful to a developing baby. So be sure to tell your provider if you are pregnant or think you may be pregnant.

Understanding results

The results will be given as positive or negative. If you have questions about your results, talk to your provider.

• Positive: Cancer was found in the sentinel lymph node and may have spread to nearby lymph nodes and/or other organs. Limitation: This result does not confirm the exact extent of spread; further testing may be needed. Next step: Your provider may recommend removing and testing more lymph nodes to check for cancer cells.
• Negative: No cancer cells were found in the sentinel lymph node, and it's unlikely that the cancer has spread. Limitation: A negative result does not guarantee that no cancer cells exist elsewhere in the body. Next step: You will not need to have any more lymph nodes removed. Continue with your provider's recommended follow-up plan.

• This procedure is only done if you have already been diagnosed with cancer.
• Sometimes, you may have more than one sentinel lymph node.
• Allergic reactions to the tracer are rare and usually mild.
• There is a small risk of infection, which can be treated with antibiotics.
• There is a low risk of lymphedema if only the sentinel lymph node is removed; risk increases with more nodes removed.

What to do next

If you have questions about your results, talk to your provider. Your provider will help plan the best treatment for you based on the results.

• What does my result mean for my cancer stage?
• Will I need additional lymph node removal or testing?
• What are the signs of infection or lymphedema I should watch for?
• How will this result affect my treatment plan?
• When should I follow up with you after the procedure?

Evidence source

U.S. National Library of Medicine: Sentinel Lymph Node Biopsy