Sentinel node biopsy is a surgical procedure used to determine if cancer has spread beyond a primary tumor into the patient’s lymphatic system. Sentinel node biopsy is used most commonly in evaluating breast cancer and melanoma.
The sentinel nodes are the first few lymph nodes into which a tumor drains. Sentinel node biopsy involves injecting a tracer material that helps the surgeon locate the sentinel nodes during surgery.
The sentinel nodes are removed and analyzed in a laboratory. If the sentinel nodes are free of cancer, then cancer isn't likely to have spread and removing additional lymph nodes is unnecessary.
If, after sentinel node biopsy, evaluation of the sentinel nodes reveals cancer, then the patient will likely need additional lymph nodes removed for the doctor to determine how far cancer has spread.
Why is it done?
Sentinel node biopsy is recommended for people with certain types of cancer in order to determine whether the cancer cells have migrated into the lymphatic system.
Sentinel node biopsy is routinely used for people with:
Sentinel node biopsy is sometimes used in other types of cancer, such as:
What are the risks associated with Sentinel Node Biopsy?
Sentinel node biopsy is generally a safe procedure but as with any surgery, sentinel node biopsy carries a risk of complications, including:
- Pain or bruising at the biopsy site
- Allergic reaction to the dye used for the procedure
- Lymphedema — a condition in which the patient’s lymph vessels are unable to adequately drain lymph fluid from an area of his body, causing fluid buildup and swelling
Although lymphedema is an unlikely 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 a few lymph nodes are removed, the risk of lymphedema following sentinel node biopsy is very small. Dozens of other lymph nodes will remain in the region of the patient’s body where the sentinel node biopsy is done. In most cases, those remaining lymph nodes can effectively process the lymph fluid.
What can the patient expect?
Locating the sentinel nodes
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 - In this option, a weak radioactive solution is injected near the tumor. This solution is taken up by the patient’s lymphatic system and travels to the sentinel nodes. This injection is usually done several hours or the day before the surgical procedure to remove the sentinel nodes.
- Blue dye - The doctor may inject a harmless blue dye into the area near the tumor. The dye is taken up by the patient’s lymphatic system and delivered to the sentinel nodes, staining them bright blue.
The blue dye is typically injected just before the surgical procedure to remove the sentinel nodes.
Whether the patients receive the radioactive solution or the blue dye or both to locate the sentinel nodes is usually determined by the surgeon's preference. Some surgeons use both techniques in the same procedure.
During sentinel node biopsy
Usually, surgeons perform sentinel node biopsy under general anesthesia, so the patient is not conscious during the procedure.
The surgeon begins by making a small incision in the area over the lymph nodes.
If the patient has received the injection of the radioactive solution prior to the procedure, the surgeon uses a small hand-held instrument called a gamma detector to determine where the radioactive solution has accumulated and identify the sentinel nodes.
If the blue dye is used, it stains the sentinel nodes bright blue, allowing the surgeon to see them.
The surgeon then removes the sentinel nodes. In most cases, there are two or three sentinel nodes, and all are removed.
The sentinel nodes are sent to a pathologist to examine under a microscope for signs of cancer.
In some cases, sentinel node biopsy is done at the same time as surgery to remove cancer. In other cases, sentinel node biopsy can be done before or after surgery to remove cancer.
After sentinel node biopsy
After sentinel node biopsy, the patient is moved to a recovery room where the healthcare team monitors him for complications from the procedure and anesthesia. If the patient doesn’t undergo additional surgery, the patient will be able to go home on the same day.
How soon the patient can return to his regular activities will depend on the situation. Talk to the doctor about the patient’s specific case.
If the patient is having sentinel node biopsy as part of a procedure to remove cancer, the patient’s hospital stay will be determined by the extent of his operation.
What are the results of this procedure?
If examination of the sentinel nodes does not show any sign of cancer, no further lymph node evaluation is needed. If further treatment is needed, the doctor will use this information to help develop the patient’s cancer treatment plan.
If any of the sentinel nodes contain cancer, the doctor may recommend having additional lymph nodes removed to determine the extent of lymph node involvement.
In certain cases, the sentinel nodes can be examined by a pathologist during the patient’s procedure. If the surgeon has this information while the patient is still in the operating room, additional lymph nodes may be removed right away. This way, the patient may not need to have another operation to remove additional lymph nodes.