Sentinel Lymph Node Biopsy

This booklet has been written as a guide for anyone thinking about having a sentinel lymph node biopsy for melanoma (a type of skin cancer). Your healthcare team will give you more detailed information as required, and will answer any questions or address any concerns you may have.

What is a sentinel lymph node biopsy?

A lymph node is part of the lymphatic system of the body. The lymphatic system is a network of vessels that carry clear fluid (called ‘lymph’) around the body. Lymph vessels lead to lymph nodes that are found in the neck, armpit, groin, chest, and abdomen. Lymph nodes are a group of cells that receives lymph from a particular area of the body.

The first lymph node is called the sentinel node. Cancer cells (from the original melanoma) can move through lymph vessels to the sentinel node where they get trapped and start growing.

If the cancer cells grow, the node can swell and be felt. In the early stage, when there are relatively few cancer cells, the lymph nodes cannot be felt through the skin. One way to assess your stage of melanoma is taking a sample of tissue (biopsy) from the sentinel lymph node.

The sentinel node that drains the primary cancer area is removed by surgery and examined under a microscope so that early spread can be identified or ruled out. This is a sentinel lymph node biopsy.

The surgery to remove the sentinel node has to be carried out at the same time as the wider local excision. This is usually undertaken under general anaesthetic as a day case procedure.

Why do I need a sentinel lymph node biopsy?

Biopsy of the sentinel lymph node is the only reliable method for finding out if the melanoma has travelled to the lymph nodes when melanoma is first detected.

If the biopsy does not show any melanoma cancer cells in the node, it usually means that the cancer has not spread from the primary site and the chance of it coming back is low. This gives most people a sense of reassurance and relief.

If the biopsy does show melanoma cancer cells, your medical care will be discussed at the Multidisciplinary Team (MDT) meeting and further treatment may be suggested as there are various options now available.

There is currently no hard evidence to show that a sentinel lymph node biopsy makes people live longer. It should be regarded as a diagnostic test providing knowledge about the stage of your cancer.

Should I have a sentinel lymph node biopsy?

The decision is yours. If this test is useful for your melanoma, your specialist will discuss the procedure and the side effects
in detail. As this is a diagnostic test, you have to make an informed decision whether or not you would like to have it done. Take your time to get as much information as you need.

Possible advantages of sentinel lymph node biopsy

  • The operation helps to find out whether the cancer has spread to the lymph nodes. It is better than ultrasound scans at finding very small cancers in the lymph nodes.
  • The operation can help predict what might happen in the future. For example, in people with a primary melanoma that is between 1 and 4mm thick, around 1 out of 10 die within 10 years if the sentinel lymph node biopsy is negative and around 3 out of 10 die within 10 years if the sentinel lymph node biopsy is positive.
  • People who have had the operation may be able to take part in clinical trials of new treatments for melanoma. These trials often cannot accept people who haven’t had this operation.
  • If you have a positive sentinel lymph node biopsy you may now be eligible for oncological treatment, in the form of drugs.

Possible disadvantages of sentinel lymph node biopsy

  • The purpose of the operation is not to cure the cancer. There is no good evidence that people who have the operation live longer than people who do not have it.
  • The result needs to be interpreted with caution. 3 in 100 (who have a negative sentinel lymph node biopsy) will then develop a recurrence in the same group of lymph nodes.
  • A general anaesthetic is needed for the operation.
  • The operation results in complications in between 4-10% of people.

How is the sentinel lymph node biopsy done?

On the day of surgery and before your operation, a small amount of radioactive tracer is injected near the site of the primary melanoma. You are then positioned under the scanner. The tracer moves from the primary site to the lymph nodes. This is scanned and recorded. The first node to take up the tracer is the sentinel node. (Note that there may be more than one node). The radiation dose from the procedure is very low, similar to a spinal X-ray.

Later on the same day, the operation will take place to remove the sentinel node and this will be done under general anaesthesia.

While you are asleep, a blue dye is injected into the area of the primary melanoma. The dye travels through the lymph vessels and is taken up by the sentinel node. The blue colour of the node(s) helps in locating them. The node(s) are removed through a small cut in the skin at the area marked during the scan.

The wider excision of the primary melanoma is also undertaken during this operation.

The removed node(s) are examined under a microscope by the histopathologist. It takes about three weeks for this to be reported.

What are the side effects of the sentinel lymph node biopsy?

  • As with any surgery, there is a small risk of bleeding, collection of fluid in the wound (seroma), and wound infection.
  • The scar from the surgery may become itchy and lumpy, although this is unlikely.
  • A small number of patients may have an allergic reaction to the blue dye.
  • There is a very slight risk of developing lymphoedema or swelling due to poor drainage of lymph in the arm or leg.
  • Urine may be blue or green after surgery due to the dye used. This clears up in a day or two.
  • The scar may also have traces of blue dye within it – this will resolve.
  • Surgery done under general anaesthetic, although very safe, can cause complications. You will have a preoperative assessment before your surgery where you can discuss any concerns.

After the sentinel lymph node biopsy

Following surgery, there may be some slight pain but this can be controlled with mild painkillers, such as Paracetamol and Ibuprofen. You may feel rather tired and should spend the first week taking it easy.

You will be able to drive once you feel safe to do so, for most people this will take about two weeks. If you need a fit note please ask. You will be able to work again once you feel able.

You will be seen in Gate 24 at Southmead or at your GP practice about a week after surgery.

Once the report (histology) is ready we will send you an appointment to be seen in clinic.

References and further information

Southmead Hospital has a drop-in centre offering a variety of activities/services. For more information, telephone 0117 414
7051 or ask your Skin Cancer CNS.

Skin Cancer Research Fund (SCaRF)
Based at Southmead Hospital
Telephone: 0117 4148755 [Last accessed January 2011]

Macmillan Cancer Support
Europe’s leading cancer information charity has over 4,500 pages of cancer information, practical advice and support for
cancer patients, their families and carers.
Telephone: 0808 800 1234 [Last accessed January 2011]

CancerHelp UK is a free information service about cancer and cancer care for people with cancer and their families.

How to contact us:

Specialist Nurse Team:
Lynda Knowles
Joanne Watson
Claire Lanfear
Samantha Wells

NGS Macmillan Wellbeing Centre
Southmead Hospital
BS10 5NB

0117 414 7415

If you or the individual you are caring for need support reading this leaflet please ask a member of staff for advice.

© North Bristol NHS Trust. This edition published March 2021. Review due March 2023. NBT002935

Sentinel Lymph Node Biopsy