A sentinel lymph node biopsy is a test that checks lymph nodes for cancer cells. Lymph nodes are part of the lymphatic system, a network of organs and vessels that help the body fight infections and other diseases. Lymph nodes are located throughout the body, including the underarms, neck, chest, abdomen, and groin.
Certain cancers, such as breast cancer and melanoma (the most dangerous form of skin cancer), can spread through the lymphatic system. Cancers spread when cells break off from the original tumor and are carried to other parts of the body. The sentinel lymph node is the first node where these types of cancers are most likely to spread. The node is usually located near the site of the original tumor. Sometimes there is more than one sentinel lymph node.
A sentinel lymph node biopsy can show how likely it is that your cancer is spreading (metastasizing).
Other names: lymph node biopsy, sentinel node biopsy, sentinel lymph node mapping and biopsy
What is it used for?
A sentinel lymph node biopsy is used to find out whether an early-stage cancer has spread through the lymphatic system. It’s most often used for people who have breast cancer or melanoma.
Why do I need a sentinel lymph node biopsy?
You may need this test if you’ve been diagnosed with breast cancer, melanoma, or certain other types of cancer. It can show whether your cancer is spreading.
What happens during a sentinel lymph node biopsy?
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. Lymphoscintigraphy takes pictures of the lymphatic system and is used to locate the sentinel lymph node. The procedure includes the following steps:
- A health care provider will apply medicine to numb the skin over the procedure area.
- You will be injected with a small amount of a radioactive substance called a tracer near the tumor. The tracer will travel and collect in the sentinel lymph node, or nodes. You may also be injected with a blue dye that stains the lymph node, making it easier to see.
- You will be given general anesthesia. General anesthesia is a medicine that makes you unconscious. It makes sure you won’t feel any pain during the surgery. A specially trained doctor called an anesthesiologist will give you this medicine.
- Once you’re unconscious, a camera will take images of the area. The camera finds and records the location of the tracer, which will have settled in the sentinel node.
- The node will be removed and sent to a lab, where it will be checked for cancer cells. This part of the test is known as a biopsy.
- The original tumor is also usually removed during the procedure.
Will I need to do anything to prepare for the test?
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 you need to do to prepare for the test.
In addition, be sure to arrange for someone to drive you home. You may be groggy and confused after you wake up from the procedure.
Are there any risks to the test?
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.
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 an unborn baby. So be sure to tell your provider if you are pregnant or think you may be pregnant.
What do the results mean?
The results will be given as positive or negative.
If your results are positive, it means cancer was found and may have spread to nearby lymph nodes and/or other organs. Your provider may recommend removing and testing more lymph nodes to check for cancer cells.
If your results are negative, it means no cancer cells were found, and it’s unlikely that the cancer has spread. You will not need to have any more lymph nodes removed.
If you have questions about your results, talk to your health care provider.
Is there anything else I need to know about a sentinel lymph node biopsy?
While sentinel lymph node biopsies are mostly used for people with breast cancer or melanoma, it is currently being studied for use with other types of cancer, including:
- Colon cancer
- Stomach cancer
- Thyroid cancer
- Non-small cell lung cancer