Sentinel Node Biopsy

What is a Sentinel Node Biopsy?

Sentinel node biopsy is an operation to remove the first lymph nodes in your armpit (axilla) that are responsible for draining the area of your breast involved by a breast cancer. This lymph node is then looked at in under a microscope to see whether there are tumour cells in it.

Several large research studies have shown the benefit of sentinel node biopsy and it is now the standard treatment for early breast cancers where the pre-operative ultrasound scan of the axilla shows no obvious signs of cancer.

What are lymph glands/nodes?

The lymphatic system is a system of lymph vessels and lymph glands throughout the body which play an important role in fighting infections and tumours. The lymph glands responsible for the breast lie mainly within your armpit, but occasionally may be within your chest or neck.

The number of lymph nodes in your armpit can vary. The average is around 15 to 20. Out of these there are 1 to 4 lymph nodes into which all the lymph fluid from the breast will first drain.

Why is it so important to know whether tumour cells are present in the lymph nodes in the arm pit?

Very important decisions regarding the overall treatment of your breast cancer are made, based on whether the lymph glands contain tumour cells. This treatment may involve further surgery, radiotherapy, hormone treatment, chemotherapy or a combination of these treatments.

What are the alternatives to this operation?

A Sentinel Node Biopsy is not a treatment for breast cancer; it is done to gain more information. The main alternative is to have the majority of the nodes removed from your armpit in an operation called Axillary Node Clearance. Problems such as pain, numbness, lymphoedema (long term fluid swelling) and shoulder stiffness can be more common following an Axillary Node Clearance.

How do you identify the sentinel lymph node?

We use a combination of 2 methods to identify the sentinel lymph nodes:

Isotope Injection

On the morning of your operation (or occasionally the day before) a small amount of radioactive material called Technetium is injected into your breast. This radioactive material is carried into your armpit by the lymph vessels and trapped in the sentinel node.

Blue Dye Injection

This is injected once you are asleep in theatre at the beginning of your operation. This dye stains the sentinel node blue so that it helps your surgeon to find the correct lymph node.

The surgery

A small cut is made in your armpit if you are having breast preserving surgery. If you are having a mastectomy, your surgeon will be able to reach the sentinel nodes through the mastectomy scar, so you won’t have an extra scar in your armpit. A hand held gamma probe used in the Operating Theatre guides your surgeon to the radioactive material injected previously. Your surgeon will remove any lymph nodes that are radioactive or blue in colour. 

What is the advantage of sentinel node biopsy?

Sentinel node biopsy is a 95% accurate way of determining the stage of your disease. It is a smaller operation than the alternative Axillary Node Clearance (where all the armpit nodes are removed) and recovery time is usually quicker, less painful and the risk of long term arm swelling is significantly lower.

What are the disadvantages of sentinel node biopsy?

In less than 5% of cases sentinel node biopsy does not accurately find disease within the armpit.

Other complications include:

  • Staining of the skin. The colour from the blue dye will stay in the breast area for several months, but it is not dangerous and will gradually fade. Very rarely, the staining can last for more than one year.
  • Blue/green urine and faeces. As the dye is flushed from your body, you may notice a bluish discolouration of your urine and your stools. This will last for 24-48 hours before returning to normal. 
  • Allergy. There is a small risk of an allergic reaction to the blue dye (less than 1%). Your surgeon will look for signs of allergy during your operation. If you do have a reaction, you will be given medication and you will be closely monitored.
  • Stiffness or limited movement in the affected arm. It is common to feel this afterwards and it will improve as the wound heals. You will be given an exercise leaflet to follow after your operation.
  • Discomfort. You may experience some discomfort afterwards. This will improve as your wounds heal. Your doctor will prescribe painkillers to help ease any pain. 
  • Numbness or tingling around the wound. This should return to normal as your body heals. If you become worried, please contact your breast team. 
  • Seroma. Sometimes a pocket of fluid will collect at the site of your biopsy – this is called a seroma. Signs of a seroma can be swelling, a feeling of fluid moving in the area and discomfort. This usually settles down by itself after 4-6 weeks. A small number of people may need to come back to the clinic to have it drained with a needle.
  • Infection. As with all operations, there can be a risk of infection. If you notice signs of infection, such as redness, or your wound becomes very painful and hot, or you have a temperature, please contact your doctor or breast care nurse to have your wound assessed. 
  • Lymphoedema. In approximately less than 5 out of 100 people the arm or breast can become swollen as a result of the surgery, this is called lymphoedema.  You will be given a leaflet called Reducing the Risk of Lymphoeodema which contains advice for you to follow. Swelling caused by lymphoedema does not usually happen straight away following surgery, but is a longer term complication.

If you do notice swelling please contact your Specialist Nurse or Medical team for advice.

Can sentinel node biopsy be unsuccessful?

Occasionally the radioactive fluid and blue dye does not find the sentinel node/s (this happens in less than 5% / one in twenty). If this happens the surgeon, during the same operation will remove approximately four nodes to make sure that the node which is likely to be the sentinel lymph node is removed. 

Does sentinel node biopsy affect whether I have a lumpectomy or mastectomy?

No – having a sentinel node biopsy will not affect whether your tumour is suitable for lumpectomy (wide local excision) or mastectomy.

What will happen if my sentinel node contains tumour?

We would discuss your case at the Multidisciplinary Team meeting. Further treatment to the remaining lymph nodes in your arm pit such as radiotherapy or more surgery is usually recommended. There may be an opportunity to enter a clinical trial.

What if the sentinel node biopsy is negative? 

If the sentinel node does not contain any breast cancer cells, you will not need any further treatment under your arm.

What if I have any further questions about sentinel node biopsy?

Please contact your Specialist Nurse or Consultant and they will be happy to help.

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 May 2021 2018. Review due May 2023. NBT003365