Sentinel node biopsy at Cheltenham Hospital

What is a sentinel node biopsy?

A sentinel node biopsy is a procedure to remove and test the first lymph node, or small group of nodes, that cancer cells are most likely to reach if they spread from a tumour. It's used in people already diagnosed with cancer, most often breast cancer or melanoma skin cancer, to help find out whether the cancer has started to spread.

Why might I need it?

You might be offered a sentinel node biopsy to check whether your cancer has spread to nearby lymph nodes, so your doctor can plan the right treatment.

For breast cancer, this is usually offered if an ultrasound or needle test of your armpit lymph nodes came back normal. For melanoma skin cancer, it depends on how thick the melanoma was when diagnosed, and whether other risk factors are present, such as broken skin (ulceration) on the melanoma or fast-dividing cancer cells.

What are the benefits of having it?

A sentinel node biopsy can tell your doctor whether cancer cells have reached your lymph nodes, which helps them plan your treatment and, for melanoma, gives you more information about what might happen in the future.

If the sentinel node is clear, you may be able to avoid more extensive lymph node surgery and its complications.

It's worth knowing that the evidence on melanoma is mixed. Having the biopsy isn't a cure, and there's no good evidence that people who have it live longer than those who don't; the results also don't always predict what will happen to you in the future.

Are there different types of test?

Yes. Your surgeon finds the sentinel nodes using one or more of the following:

• a small amount of radioactive liquid, injected before your operation, which a handheld scanner can detect
• a blue dye, injected during your operation, which stains the sentinel nodes so they're easier to see
• a magnetic tracer, an alternative to the radioactive liquid, detected using a magnetic probe.

Most surgeons use a combination of these, which helps them identify the sentinel nodes in more than 95% of patients.

How do I prepare for the test?

You'll usually have a pre-assessment appointment in the 2 weeks or so before your operation. Staff will ask about your health and current medicines, check your weight, blood pressure, pulse and temperature, and tell you when to stop eating, drinking, or taking certain medicines beforehand.

Tell your care team if you:

• have any allergies or sensitivities, including to iodine, latex, tape, or anaesthetic
• have a history of bleeding problems, or take blood-thinning medication
• are pregnant, breastfeeding, or think you might be pregnant.

For melanoma, you may also be given a special scan called a lymphoscintigram, either the day before or the morning of your biopsy, to show where your sentinel nodes are.

What happens during the test?

1. You'll be given a general anaesthetic, so you'll be asleep throughout
2. If you haven't already had one before your operation, your surgeon injects a radioactive liquid, a blue dye, or both, near where the cancer was
3. Using a handheld scanner or by looking for the blue staining, your surgeon locates the sentinel node or nodes
4. They make a small cut and remove the sentinel node, or up to around four nodes
5. The node is sent to a laboratory to check for cancer cells – in some hospitals, an initial result can be ready during the operation itself, so more nodes can be removed straightaway if needed
6. Your surgeon closes the wound with stitches, which are often dissolvable, and may leave a small drain in place to collect any fluid.

For breast cancer, this is usually done during the same operation as removing the tumour. For melanoma, it's usually done at the same time as the operation to remove the skin and tissue around where the melanoma was.

What happens after the test?

You'll usually go home the same day, though you may need to stay overnight if you've had additional surgery or need extra monitoring. You'll need an adult to drive you home and to stay with you for at least the first 24 hours, since you've had a general anaesthetic.

Some pain, bruising and swelling around the wound is normal, and you'll be given painkillers to help. If you had the blue dye, your skin near the wound may look discoloured for some time, and your urine may look blue or green for a day or two; this is harmless.

Most people can gradually resume normal activities over 2 to 4 weeks, and time off work is often around 2 weeks, though this depends on your job and how you're healing.

Your results usually take 1 to 2 weeks. You'll have a follow-up appointment to discuss them and any further treatment you might need.

What are the risks?

As with any operation, there are some risks:

• an allergic reaction to the blue dye, which can range from a mild rash to a serious reaction, though this is rare
• infection, seroma (a build-up of fluid) or a haematoma (a collection of blood) near the wound
• numbness, tingling, or a burning or stabbing pain if a nerve is irritated during surgery
• stiffness in the nearby joint, such as your shoulder
• lymphoedema, a swelling caused by fluid that can't drain away properly – this is usually temporary, but can occasionally be permanent
• a small chance of a false-negative result, where cancer cells are present but not found in the sentinel node, which could give a falsely reassuring picture.

Removing only the sentinel node or nodes, rather than all the nodes in the area, means these risks are generally lower than with more extensive lymph node surgery.