Sentinel Node Biopsy
What are lymph nodes?
Lymph nodes (also known as lymph glands) are small glands that filter waste fluid and debris. They are part of the body’s immune system. The lymph nodes that filter cells from the breast are mainly located in the axilla (armpit). If breast cancer cells spread beyond the breast, the lymph nodes in the axilla are usually the first ones affected. Other lymph nodes that can be involved with breast cancer are located near the collarbone (clavicle) and beside the breastbone (sternum).
Why do lymph nodes need to be removed?
Breast cancer treatment usually involves removing some lymph nodes in addition to removing the cancer from the breast. Testing the lymph nodes gives us important information about the breast cancer and helps plan further treatment.
In the past, the usual procedure was to remove most, if not all of the lymph nodes in the axilla (armpit), an operation called an axillary lymph node dissection or axillary clearance to assess the lymph nodes. Sentinel lymph node biopsy has now replaced axillary lymph node dissection in most patients with early breast cancer. Research has demonstrated that sentinel lymph node biopsy is an accurate test in many studies internationally but there is still a 5% false negative rate (i.e. a risk of not removing a lymph node with cancer within).
What is sentinel lymph node biopsy (SNB)?
The aim of SNB is to remove some lymph nodes (usually 2 – 3) in the axilla. The sentinel nodes are usually the first lymph nodes to which breast cancer spreads. It is thought that if breast cancer cells were to spread out of the breast, they would travel to the sentinel node/s before moving on to other nodes and the rest of the body.
The lymph nodes are then examined by a pathologist to see if there are any cancer cells present. This information is used to help guide further treatment.
SNB removes fewer lymph nodes than an axillary clearance. This lowers the risk of developing lymphoedema, pain and numbness.
How are the sentinel nodes found?
The sentinel node is identified or “mapped” using a combination of techniques. These are:
Lymphoscintigraphy (lymphatic mapping)
This is usually performed the day before or morning of surgery. A small amount of radioactive tracer is injected around the cancer or under the nipple. The radioactive tracer travels from the cancer site to the sentinel node and is retained in the lymph node. This makes the sentinel node radioactive so that that a special probe can be used in the surgery to find the node.
Blue Dye
When you are asleep for the operation, Dr Graham will inject a small amount of blue dye around the nipple or the cancer. The dye quickly moves into lymphatic channels and makes the sentinel lymph nodes appear blue and therefore easier to identify.
The combination of lymphoscintography and blue dye together allows a sentinel node to be identified more accurately, but in some cases only one of the two methods may be used.
What happens if the sentinel node is positive?
Any nodes that are removed are carefully looked at under the microscope by a pathologist. If the pathologist sees cancer cells in the node it is said to be “positive”. If the node is positive, it may be necessary to have further surgery to remove more lymph nodes in the axilla or radiotherapy to the glands.
If the sentinel nodes are not positive, no further surgery is needed, but other treatments may still be required depending on the other characteristics of your cancer.
How long is the operation and what is the recovery like?
Everyone is different, but for most patients the operation takes about 1 hour. Sentinel lymph node biopsy is usually done in conjunction with another procedure, so the length of operation and when you can go home depends on what other procedure is being done.
A waterproof dressing will be placed on your wound. You will be able to do most things for yourself immediately after the operation and are encouraged to do so. While you are in hospital, you will be given exercises to do to help with shoulder function and range of movement.
What are the complications of a sentinel lymph node biopsy?
All operations have potential side effects and complications. Fortunately, these are uncommon and surgery usually proceeds without any problems. Dr Graham will the risks and possible complications with you in detail at your consultation.
These complications include but are not limited to bleeding, seroma, infection, staining of the skin from blue dye, allergy to blue dye, altered sensation, lymphoedema and cording.
Dr Graham advocates the National Law and Australian Health Practitioner Regulation Agency (AHPRA) guidelines that any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.