Sentinel lymph node biopsy: Remove, and examine to determine whether cancer cells are present
Introduction to SLNB:
A sentinel lymph node biopsy (SLNB) is a diagnostic procedure aimed at determining whether the cancer has spread into the lymph node(s) that drains that particular area of skin. It is most commonly performed for certain types of melanoma but is also a useful test for Merkel cell carcinoma.
Lymph nodes are best considered as the body’s processing stations. Typically, they help process and present infections to the body’s immune system, but they are also often a site that cancers can spread to. Most lymph nodes relevant to skin cancer are based in the groin (5-10 nodes), arm pit (10-20 nodes) and neck (20-40 nodes). These sites are, therefore, the areas where the SLNB is taken from.
The SLNB needs to be performed at the same time as the wider local excision of the melanoma/biopsy scar itself. This is so that we can accurately determine the exact lymph node that drains the area of skin where the melanoma itself was situated.
It is critical to accurately determine the correct lymph node(s). As a result, you will require a special nuclear medicine localisation scan on the morning of/day before surgery and I will use a Geiger counter and some blue dye to give us a 95% accuracy rate.
Key details:
- Duration: 45 to 90 minutes
- Cost: $12000 to $20000
- Anaesthetic: General anaesthetic
- Length of stay: Day stay or 1 night in hospital
Post-surgery care and downtime:
Showering: You can shower the wounds with the dressings in place after 48 hours.
Exercise: Light exercise 1-week post-op, strenuous exercise 4 weeks post-op
Driving: 2 days after surgery if able to do an emergency stop
Work: Desk-based work after 2 days. Heavy work after 4 weeks.
Frequently asked questions:
What are the risks and complications of a sentinel lymph node biopsy?
Alongside the standard risks of any general anaesthetic procedure, the specific risks relevant to a SLNB are numbness around the scar, fluid collections requiring drainage with a needle and syringe (seroma), allergic reactions, not being able to find the sentinel node and a 0.5% risk of persistent swelling in the arm or leg for SLNB from the arm pit or groin (lymphoedema).
What are the implications if the sentinel lymph node biopsy shows the cancer has spread?
The SLNB result tells us a lot of information about how the cancer is behaving. If there is evidence of cancer in the lymph node then this changes the overall risk of the cancer spreading elsewhere in the body or being potentially fatal. Additional scans will be performed to check the rest of your body and there are other treatment options available that have been shown to reduce the risk of further cancer recurrence. Very occasionally, further surgery is warranted, but this primarily reduces the chance of further cancer within the area the SLNB was taken from, rather than reducing the risk of it spreading elsewhere.
Are there alternative options to a sentinel lymph node biopsy?
In patients who meet the criteria for a SLNB, but choose not to have the procedure, we tend to recommend monitoring ultrasound scanning of the lymph nodes that would normally drain the initial skin cancer area. It should be noted that this is less accurate and will only identify cancer spread once it has become large enough to see on the ultrasound.