To help doctors give their patients the best possible care, the American Society of Clinical Oncology (ASCO) and the Society of Surgical Oncology (SSO) developed evidence-based recommendations on sentinel lymph node biopsy for melanoma. This guide for patients is based on the ASCO and SSO recommendations.
- A sentinel lymph node biopsy is a procedure that helps the doctor find out whether melanoma has spread to the lymph nodes.
- If melanoma is found during a sentinel lymph node biopsy, the doctor should remove more lymph nodes.
Talk with your doctor about what kind of procedure is needed to evaluate and treat your melanoma and what the results will mean.
Melanoma is a type of cancer that starts in color-producing cells of the skin called melanocytes. Often, but not always, melanoma develops from an existing mole. Melanoma can grow deep into the inner layers of skin and spread to the lymph nodes (tiny, bean-shaped organs that help fight infection) and other parts of the body. Treatment for melanoma is determined by the thickness (how deep the tumor has grown into the layers of the skin) of the primary tumor and whether it has spread. This is also called the stage of the cancer. Whether melanoma has spread to the lymph nodes is one of the most important factors in determining a patient’s prognosis (chance of recovery).
A sentinel lymph node biopsy (also called sentinel node biopsy or SNB) is a procedure that helps the doctor find out whether the cancer has spread to the lymph nodes. When cancer spreads from the place it started to the lymph nodes, it travels through the lymphatic system. A sentinel lymph node is the first node into which the lymphatic system drains. Because melanoma can start anywhere on the skin, the location of the sentinel lymph nodes will be different depending on where the cancer started. To find the sentinel lymph node, a harmless radioactive substance is injected as close as possible to where the melanoma started. The substance is followed to the sentinel lymph node. Then, the doctor removes one or a few of these lymph nodes to check for melanoma cells, leaving behind most of the other lymph nodes in that area.
If the biopsy results show that the cancer has not spread to the sentinel lymph node, then no additional lymph node surgery is needed. However, if melanoma is found in the sentinel lymph nodes, a lymph node dissection is usually recommended. A lymph node dissection is the surgical removal of the remaining lymph nodes in that area. The risks of a lymph node dissection vary depending on the number of lymph nodes removed during the procedure.
ASCO and the SSO developed the following recommendations on the use of SNB and lymph node dissection for melanoma:
- SNB is recommended for patients with a melanoma that developed on any part of the surface of the skin and is 1 millimeter (mm) to 4 mm thick.
- SNB may be recommended to help stage and determine treatment for a melanoma that is thicker than 4 mm.
- SNB is not recommended for most patients with a thin melanoma (less than 1 mm thick), although it may be considered if the melanoma has a high risk of spreading. It is not yet certain which patients with a thin melanoma have a higher risk of the disease spreading to the lymph nodes. However, some high-risk features of melanoma include ulceration (the outer layer of skin over the melanoma is missing when viewed under a microscope) or a high mitotic rate (more cells that are dividing; a sign that the cancer may be growing rapidly).
A lymph node dissection is recommended for all patients when melanoma is found in the sentinel lymph nodes.
What This Means for Patients
For many patients with a melanoma thicker than 1 mm, SNB is a useful way to find out whether the cancer has spread from where it began. It helps your doctor plan treatment and can help you understand your prognosis. There are few side effects from the procedure, but a patient may experience infection, seroma (fluid build-up) near the surgical area, numbness, and re-opening of the surgical area. Rarely, lymphedema (build-up of lymph fluid) may occur. However, this side effect is more common for patients who have had a lymph node dissection.
If melanoma is found in the sentinel lymph nodes, a lymph node dissection to remove the remaining lymph nodes in that area allows the doctors to find out whether the cancer has spread and remove any additional lymph nodes that may contain melanoma. A patient may take longer to recover after a lymph node dissection and has a higher risk of side effects. For example, a patient who has had a lymph node dissection in the armpit or groin has a higher risk of lymphedema. However, the results of a lymph node dissection help your doctor make sure you get the appropriate treatment for your stage of melanoma. Talk with your doctor about the tests needed to diagnose melanoma and determine the stage, and how these results affect your treatment options.
Questions to Ask the Doctor
Consider asking the following questions of your doctor:
- Do you recommend that I have a SNB? Why or why not?
- Where is the sentinel lymph node located for my specific melanoma?
- What are the risks of SNB?
- When will I know the results and who will explain them to me?
- What further tests will be needed if the results indicate cancer?
- Will I need a lymph node dissection?
- What are the risks of a lymph node dissection?
- If I need a lymph node dissection, what can I do to prevent lymphedema?
- What follow-up care will I need after a SNB and/or a lymph node dissection?
- What clinical trials are available for patients with melanoma that has spread to the lymph nodes?
Read the entire clinical practice guideline available at www.asco.org/guidelines/snbmelanoma.