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Definition
Sentinel node biopsy is a surgical procedure used to determine if cancer has spread beyond a primary tumor into your lymphatic system. It's used most commonly in evaluating breast cancer and melanoma.
The sentinel lymph node is the first lymph node into which a tumor drains. Sentinel node biopsy involves finding the sentinel lymph node before surgery, and then removing the node during surgery. If, following a sentinel node biopsy, evaulation shows that the sentinel lymph node is free of cancer, the cancer isn't likely to have spread and removing additional lymph nodes is unnecessary.
If, after sentinel node biopsy, evaluation of the sentinel lymph node reveals cancer, then you'll likely need additional lymph nodes removed for your doctor to determine how far the cancer has spread.
Why it's done
Your lymphatic system circulates protein-rich lymph fluid throughout your body. This fluid collects bacteria, viruses and waste products and carries them through your lymph vessels, which lead to small round organs called lymph nodes. The wastes are then filtered out by lymphocytes — infection-fighting cells that live in your lymph nodes — and are ultimately flushed from your body. Groups of lymph nodes are found in your neck, underarms, chest, abdomen and groin.
Most cancers spread (metastasize) in an orderly way through your body's lymphatic system. The first lymph node to which a tumor drains lymph fluid is called the sentinel node. If cancer has spread to your lymphatic system, this node is the most likely to contain cancer. Surgically removing and then examining a sentinel lymph node for cancer allows your doctor to determine if your cancer has spread and to plan additional evaluation and treatment accordingly.
Sentinel node biopsy isn't helpful for all types of cancer. The procedure is most effective, and most frequently recommended, for people with the following types of cancer:
Other types of cancer for which sentinel node biopsy may be appropriate include:
- Vulvar cancer
- Cervical cancer
- Endometrial cancer
- Prostate cancer
- Squamous head and neck cancer
- Thyroid cancer
- Non-small cell lung cancer
- Merkel cell carcinoma
Risks
Sentinel node biopsy is generally a safe procedure. But as with any surgery, sentinel node biopsy carries a risk of complications.
Potential complications include:
- Bleeding
- Pain or bruising at the biopsy site
- Infection
- Allergic reaction to the dye used for the procedure
- Lymphedema — a condition in which your lymph vessels are unable to adequately drain lymph fluid from an area of your body, causing fluid buildup and swelling
Lymphedema
Although lymphedema is a possible complication of sentinel node biopsy, one of the main reasons sentinel node biopsy was developed was to decrease the chance of developing lymphedema, which is more likely to occur if many lymph nodes are removed from one area. Because only one or, at most, a few lymph nodes are removed, the risk of lymphedema following sentinel lymph node biopsy is very small. Dozens of other lymph nodes will remain in the region of your body where the sentinel node biopsy is done. In most cases, those remaining lymph nodes can effectively process the lymph fluid.
How you prepare
You may need to avoid eating and drinking for a certain period of time before the procedure to avoid anesthesia complications. Your doctor will provide specific instructions.
What you can expect
Locating the sentinel node
The first step in a sentinel node biopsy is to locate the sentinel node. There are two options for locating the sentinel node:
- Radioactive solution. Your doctor may inject a weak radioactive solution near the tumor. This solution is taken up by your lymphatic system and travels to the sentinel node. This injection is usually done several hours before the surgical procedure to remove the sentinel node.
- Blue dye. Your doctor may inject a harmless blue dye into the area near the tumor. The dye is taken up by your lymphatic system and delivered to the sentinel node, staining it bright blue. The blue dye is typically injected just before the surgical procedure to remove the sentinel node.
Whether you receive the radioactive solution or the blue dye to locate the sentinel node is usually determined by your surgeon's preference. Some surgeons use both techniques in the same procedure to double-check the sentinel node identification.
During sentinel node biopsy
Surgeons perform sentinel node biopsy during general anesthesia, so you're unconscious during the procedure. The anesthesiologist or anesthetist gives you an anesthetic medication as a gas — to breathe through a mask — or injects a liquid medication into a vein.
The surgical team places several monitors on your body to help make sure that your heart rate, blood pressure and blood oxygen remain at safe levels throughout the procedure. These monitors include a blood pressure cuff on your arm and heart-monitor leads attached to your chest.
Once you're unconscious, the surgeon makes a small incision in the area over the lymph nodes. If your surgeon has injected the radioactive solution prior to the procedure, he or she uses a small hand-held instrument called a gamma detector to determine where the radioactivity has accumulated and identify the sentinel node. If the blue dye is used, it stains the sentinel lymph node bright blue, allowing the surgeon to see it. The surgeon then removes the sentinel node. In some cases, there may be two or three sentinel nodes, and all are removed. After removal, the sentinel node(s) is sent to a pathologist to examine under a microscope for signs of cancer.
If you have breast cancer, sentinel node biopsy may be performed during lumpectomy or mastectomy.
After sentinel node biopsy
After a sentinel node biopsy, you're moved to a recovery room where the health care team monitors you for complications from the procedure and anesthesia. If there aren't any complications, you'll be able to go home within a few hours. You can usually return to your regular activities within several days, and the incision will heal within a few weeks. Talk to your doctor about specific activity restrictions.
If you have sentinel node biopsy as part of a mastectomy or lumpectomy, you may remain in the hospital longer and have additional activity restrictions.
Results
If examination of the sentinel node does not show any sign of cancer, no further lymph node evaluation is needed, and your doctor will use this information to help develop your cancer treatment plan, if further treatment is needed.
If the sentinel node does contain cancer, you'll likely need to have additional lymph nodes removed to determine the extent of lymph node involvement.
A few medical institutions use a technique called frozen section to evaluate the lymph node tissue and gain preliminary information about its status during the sentinel node biopsy procedure. If your surgeon has this information while you're still in the operating room, and it shows that the sentinel node is cancerous, you may not have to undergo another operation. Instead, additional lymph nodes may be removed at that time. In most situations, however, additional lymph node removal is done during a separate procedure at a later date.
Last Updated: 2009-10-17
