SENTINEL LYMPH NODE BIOPSY

WHAT ARE LYMPH NODES?

Also known as lymph glands
Part of our immune system
Filter tissue fluid from all over the body before that fluid is returned into the blood stream
Breast tissue fluid predominantly drains through tiny channels (lymphatics) up to lymph nodes under the arm (axillary lymph nodes) but can also drain to lymph nodes behind the breast bone (internal mammary lymph nodes)
Breast cancer cells can spread in the tissue fluid through lymphatics to lymph nodes where secondary cancer deposits may develop

Under the arm, there are approximately 20-40 lymph nodes
The Sentinel Lymph Node is the first node breast tissue fluid drains to
Removing the Sentinel Lymph Node - usually at time of the main breast cancer operation - allows us to analyse it carefully for evidence of breast cancer spread – this is known as Sentinel Lymph Node Biopsy
Often there may be more than one sentinel node – a usual number is two or three

Prior to surgery (the morning of or afternoon before), radioactive dye is injected into the affected breast – apart from the injection itself, this is painless and not harmful
The radioactive dye travels in the tissue fluid through the breast’s lymphatic channels to the first group of lymph nodes where it lodges
Scanning is performed to show which lymph node/s become/s radioactive
This/these are the breast’s sentinel lymph nodes – the first one/s tissue fluid drains through
Later on, in the operation, your surgeon can find this/these node/s with the aid of a radioactive probe
In addition, your surgeon will inject a blue dye into the breast when you are asleep but before the operation starts – this dye also travels to the sentinel lymph nodes and is a second way to help identify them
Any radioactive and/or blue lymph nodes are removed and sent away for analysis
On average, two or three lymph nodes will be removed.

On average, about two thirds of women with breast cancer in Australia will not have cancerous lymph nodes
Sentinel lymph node biopsy is about 95% accurate in identifying these women and can spare them having all of their axillary lymph nodes removed (axillary clearance) unnecessarily
If the sentinel lymph node biopsy does show cancerous nodes, this is important information in guiding further treatment – which can initially mean axillary clearance

If both radioactive and blue dye is used, a sentinel lymph node will be found in approximately 98% of cases – only rarely will no lymph node become radioactive or blue
As mentioned in the previous section, a sentinel lymph node biopsy is about 95% accurate in telling us if breast cancer has spread to the lymph nodes or not

No
If testing before your operation shows cancerous lymph nodes, the sentinel lymph node biopsy is unnecessary as we already know what it is otherwise designed to tell us – full lymph node removal (axillary clearance) will usually be recommended instead
Non-invasive cancers (Ductal Carcinoma In Situ or DCIS) usually don’t require sentinel lymph node biopsy as they haven’t yet learned the skill of invading into lymphatics and thus lymph nodes
Sentinel lymph node biopsy is most commonly used in women with early invasive breast cancers – where the chance of cancerous lymph nodes is low

As mentioned above, about two thirds of Australian women with breast cancer will not have cancerous lymph nodes – sentinel lymph node biopsy allows these women to avoid having all their axillary lymph nodes removed
Axillary Clearance is associated with a higher risk of short, medium and long term side effects than sentinel lymph node biopsy alone
Side effects may include chronic arm swelling (lymphoedema), shoulder stiffness and nerve damage