A sentinel node biopsy removes the first one or few lymph nodes that drain lymph fluid from a cancer site so they can be examined for cancer cells. It can be used in both breast cancer and melanoma because these cancers may spread through the lymphatic system.
If sentinel node biopsy has been included in your surgical plan, understanding what the test is for, how the node is found, what happens during the procedure and what the results may mean can make the process easier to follow.
The key point: sentinel node biopsy is primarily a staging procedure. It helps determine whether cancer cells have reached the first draining lymph node or nodes and can provide information that helps your treating team plan further care.
What Is a Sentinel Lymph Node?
Lymph nodes are small structures that form part of the lymphatic and immune systems. They filter lymph fluid as it travels through the body and are found in groups in areas including the armpits, groin and neck.
A sentinel lymph node is the first lymph node, or one of the first few nodes, that receives lymph drainage from an area containing a cancer.
Why check the first draining node?
If cancer has started travelling through the lymphatic system, the sentinel node is one of the first places cancer cells may be found. Examining that node can provide staging information without automatically removing a larger group of lymph nodes.
Why Lymph Nodes Are Checked in Breast Cancer and Melanoma
Lymph-node involvement can affect cancer staging and may influence whether additional treatment is discussed.
| Question | Breast cancer | Melanoma |
|---|---|---|
| Why check the nodes? | To assess whether breast cancer cells are present in the first draining lymph nodes and help guide further treatment. | To provide staging information in selected melanomas and assess whether melanoma cells have reached a draining lymph node. |
| Where are the sentinel nodes? | Usually in the armpit on the same side as the breast cancer. | They may be in the armpit, groin, neck or another drainage area depending on the melanoma's location. |
| Does everyone need the procedure? | No. Whether sentinel node biopsy is recommended depends on the breast diagnosis and clinical circumstances. | No. The melanoma's thickness and other pathological features help determine whether sentinel node biopsy should be discussed. |
Potential benefit: sentinel node biopsy can provide staging information while removing fewer lymph nodes than a full lymph-node dissection.
Risks and limitations: the procedure can cause bleeding, infection, pain, numbness, fluid collection, restricted movement and lymphoedema. Sentinel node biopsy is not completely accurate in every case, and further treatment may still be needed depending on the pathology result.
Sources: Cancer Australia: Sentinel node biopsy and Cancer Council: Melanoma guide to cancer care.
How the Sentinel Node Is Found
The sentinel node usually looks like the surrounding lymph nodes, so a mapping technique is used to identify it.
Radioactive tracerA small amount of radioactive tracer may be injected near the cancer or previous biopsy site. The tracer travels through the lymphatic channels towards the sentinel node. A scan may be used to map the drainage pathway, particularly for melanoma, and a handheld probe can help the surgeon locate the node during the operation. Potential benefit: the tracer helps identify the node most likely to receive lymphatic drainage from the cancer area. Risks and limitations: the injection can sting, and allergic reactions are possible, although severe reactions are uncommon. |
Blue dyeBlue dye may also be injected so that lymphatic channels and the sentinel node can be seen during surgery. The node may turn blue, helping the surgeon identify it. Potential benefit: blue dye can provide a visual method of identifying the sentinel node. Risks and limitations: allergic reactions can occur. Blue or green discolouration of urine and temporary staining of the skin can also occur after the dye is used. |
Sources: Cancer Australia and Healthdirect: Sentinel node biopsy.
What Happens on the Day of a Sentinel Node Biopsy?
Your surgical team will give you instructions about fasting, medicines and when to arrive. Tell your team about your medicines, allergies and any blood-thinning medication you take.
1. Lymphatic mapping
A radioactive tracer may be injected before surgery so the drainage pathway and sentinel node can be identified.
2. Anaesthetic
Sentinel node biopsy is generally performed under general anaesthetic as part of the planned cancer operation.
3. The sentinel node is identified
The surgeon uses the tracer signal and, where used, blue dye to locate the first draining lymph node or nodes.
4. The node is removed
A small incision is made and the identified node or nodes are removed for pathological examination.
5. The wound is closed
The incision is closed and you are monitored during recovery from the anaesthetic.
Often performed with the main operation: sentinel node biopsy is commonly performed during breast surgery or during the wider excision of a melanoma when it is clinically indicated. The exact timing depends on your treatment plan.
Sentinel Node Biopsy for Breast Cancer
In breast cancer, the sentinel lymph nodes are usually located in the armpit. Sentinel node biopsy may be recommended when the result is expected to provide useful staging information.
Cancer Australia notes that sentinel node biopsy is usually performed during breast-conserving surgery or mastectomy, although it can sometimes be performed separately.
DCIS is different: Cancer Australia's updated breast cancer guidance states that sentinel node biopsy should not routinely be offered to patients with DCIS undergoing breast-conserving surgery unless clinically indicated.
Source: Cancer Australia: The 12 Practices.
Sentinel Node Biopsy for Melanoma
Sentinel node biopsy is not required for every melanoma. It may be discussed when the melanoma's pathological features indicate that additional staging information could be useful.
Because lymphatic drainage depends on where the melanoma is located, the sentinel node may be in the armpit, groin, neck or another area.
Why lymphatic mapping matters in melanoma: skin on different parts of the body drains to different lymph-node groups. Mapping helps identify which node or nodes receive lymph from the melanoma site.
Source: Cancer Council: Melanoma guide to cancer care.
Understanding Your Sentinel Node Results
The removed sentinel node or nodes are sent to a pathology laboratory and examined under a microscope.
| Result | What it means | What may happen next |
|---|---|---|
| Negative sentinel node | Cancer cells were not identified in the sentinel node or nodes examined. | Your treating team considers this result together with the primary cancer pathology when planning further treatment. |
| Positive sentinel node | Cancer cells were identified in one or more sentinel nodes. | Further surgery, radiotherapy, systemic treatment, surveillance or specialist referral may be discussed depending on the cancer and individual circumstances. |
A positive sentinel node does not automatically mean more lymph nodes must be removed. Management depends on the cancer type, the amount of disease found, the primary cancer treatment and other clinical factors.
What Happens If Cancer Is Found in the Sentinel Node?
The next step depends on whether the sentinel node biopsy was performed for breast cancer or melanoma and on the rest of your pathology.
| Condition | Possible next steps |
|---|---|
| Breast cancer | Further axillary treatment may be considered, but not every positive sentinel node requires additional lymph-node surgery. Radiotherapy and systemic treatment may also form part of the treatment plan. |
| Melanoma | The result contributes to melanoma staging. Further imaging, surveillance and discussion with a medical oncologist may be recommended depending on the stage and other pathology findings. |
Your multidisciplinary team considers the sentinel node result together with all other available information before recommending further treatment.
Recovery After Sentinel Node Biopsy
Recovery depends partly on whether sentinel node biopsy is performed alone or together with a larger breast or melanoma operation.
Possible early effects can include:
- pain or tenderness around the incision;
- bruising;
- swelling;
- temporary stiffness;
- numbness or altered sensation near the wound;
- a fluid collection called a seroma; and
- temporary blue or green discolouration if blue dye was used.
When to contact your treating team: follow the discharge instructions provided to you. Contact your treating team if you develop symptoms they have asked you to watch for, such as increasing redness, worsening swelling, wound discharge, fever or another unexpected change.
Lymphoedema After Sentinel Node Biopsy
Lymphoedema is swelling caused by a build-up of lymph fluid. In breast cancer treatment it may affect the arm, hand or breast. After melanoma treatment, the area affected depends on which lymph-node group was assessed.
Lower risk than more extensive node surgery
Cancer Australia reports that sentinel node biopsy is associated with a lower risk of arm problems such as numbness, shoulder stiffness and lymphoedema than axillary lymph node dissection.
Potential benefit: removing fewer lymph nodes reduces the amount of disruption to lymphatic drainage compared with more extensive node surgery.
Risk: lymphoedema can still occur after sentinel node biopsy. Swelling, heaviness, tightness or persistent changes should be reported to your treating team.
Sources: Cancer Australia and Healthdirect.
Sentinel Node Biopsy Compared with Axillary Lymph Node Dissection
Sentinel node biopsy removes a small number of selected lymph nodes. Axillary lymph node dissection, also called axillary clearance, removes a larger group of lymph nodes from the armpit.
| Feature | Sentinel node biopsy | Axillary lymph node dissection |
|---|---|---|
| Number of nodes removed | Usually the first one or few sentinel nodes. | A larger group of lymph nodes is removed from the armpit. |
| Main purpose | Primarily staging and assessing whether cancer has reached the first draining nodes. | Used in selected situations when more extensive axillary treatment is required. |
| Lymphoedema risk | Lower than with axillary lymph node dissection. | Higher because more lymph nodes and lymphatic channels are affected. |
| Numbness and shoulder stiffness | Lower risk. | Higher risk. |
Why sentinel node biopsy may be used first: when clinically appropriate, it can provide lymph-node staging information while limiting the amount of lymph-node tissue removed.
Limitation: in some situations more extensive lymph-node treatment may still be recommended depending on the pathology and cancer treatment plan.
Questions to Ask Before a Sentinel Node Biopsy
It can help to write down your questions before meeting your surgeon.
- Why is sentinel node biopsy being recommended for me?
- What information are you expecting the result to provide?
- Will a radioactive tracer, blue dye or both be used?
- Will the procedure be performed at the same time as my main operation?
- How many sentinel nodes do you expect to remove?
- What are the potential benefits and risks in my case?
- What is my risk of lymphoedema?
- What symptoms should I watch for after surgery?
- When is the pathology result likely to be discussed with me?
- What could happen next if cancer cells are found?
Sentinel Node Biopsy on the Gold Coast
Dr John Gault provides sentinel node biopsy as part of the surgical management of breast cancer and melanoma on the Gold Coast. He completed Fellowship in General Surgery with the Royal Australasian College of Surgeons and holds the qualification FRACS.
Dr Gault consults at Gault Surgery in Pindara Place, Benowa and operates at Pindara Private Hospital. Breast care nurse support is available as part of the breast care team. The nurse is not named on this page so the information remains accurate if staffing changes.
Public and private care: Seeing Dr Gault privately does not change your place on a public hospital waiting list.
Preparing for your consultation
1. Bring your reports.
Bring any available imaging, biopsy reports, pathology reports and other relevant medical information.
2. Ask why sentinel node biopsy is being considered.
Understanding how the result may affect staging or treatment can help you understand the purpose of the procedure.
3. Discuss the risks.
Ask about bleeding, infection, numbness, seroma, lymphoedema, allergic reaction and any risks specific to your planned operation.
4. Arrange a referral.
A referral from your GP or another treating doctor allows eligible patients to claim the applicable Medicare rebate for a specialist medical consultation.
5. Contact the rooms.
Gault Surgery can be contacted on (07) 5539 3999.
Frequently Asked Questions About Sentinel Node Biopsy
What is a sentinel node biopsy?
A sentinel node biopsy removes the first lymph node or small group of nodes that drain the area containing a cancer. The nodes are examined by a pathologist to see whether cancer cells are present.
Why is sentinel node biopsy used for breast cancer?
It can provide information about whether breast cancer cells have reached the first draining lymph nodes, which helps with staging and treatment planning. The procedure is not required in every breast cancer situation.
Why is sentinel node biopsy used for melanoma?
For selected melanomas, sentinel node biopsy can provide staging information by showing whether melanoma cells have reached the first draining lymph node. Not every melanoma requires the procedure.
How is the sentinel lymph node found?
A radioactive tracer may be injected near the cancer or biopsy site so the lymphatic drainage pathway can be mapped. Blue dye may also be used during surgery. The surgeon uses the tracer signal and, where applicable, the dye to identify the sentinel node or nodes.
Does a positive sentinel node mean I need more lymph nodes removed?
Not automatically. The next step depends on the type of cancer, the amount of cancer found in the node, the treatment already planned and other clinical factors. Further surgery, radiotherapy, systemic treatment or surveillance may be discussed.
Can sentinel node biopsy cause lymphoedema?
Yes. Lymphoedema can occur after sentinel node biopsy, although Cancer Australia reports that the risk is lower than after axillary lymph node dissection. Your individual risk depends on the surgery and other treatment you receive.
What are the other risks of sentinel node biopsy?
Possible risks include bleeding, infection, bruising, pain, numbness, seroma, stiffness, lymphoedema and allergic reaction to the tracer or blue dye. Blue dye can also cause temporary discolouration. Your surgeon can discuss the risks relevant to your procedure.
Where does Dr John Gault perform sentinel node biopsy on the Gold Coast?
Dr John Gault consults at Gault Surgery in Pindara Place, Benowa and performs surgery at Pindara Private Hospital. The rooms can be contacted on (07) 5539 3999.
Discussing Sentinel Node Biopsy on the Gold Coast
Sources and Further Reading
- Cancer Australia: Sentinel node biopsy
- Cancer Australia: The 12 Practices
- Healthdirect: Sentinel node biopsy
- Cancer Council: Melanoma guide to cancer care
- Cancer Council: Clinical practice guidelines for melanoma
- Melanoma Institute Australia
This page provides general information only. Your diagnosis, pathology, imaging, medical history and individual circumstances need to be considered by your treating medical team when treatment is planned.