Sentinel Lymph Node Biopsy

What is it?

The most common place that melanoma skin cancer spreads to is the nearby lymph nodes. If your melanoma is deeper than 1mm (stage IB to IIC) or if there are additional risk factors, your specialist should offer you a sentinel lymph node biopsy. The lymph nodes are arranged like a bunch of grapes, the sentinel lymph node biopsy allows your doctor to identify the ‘grape’ or node within the bunch and then remove it for analysis. This node is the most likely lymph node to be affected by your melanoma.  The procedure has two parts; the first occurs in the nuclear medicine department where a safe radioactive dye is injected around your melanoma or scar where your melanoma was, the dye travels in lymphatic channels to where the lymph nodes are, several marks are then drawn on the skin. The second part takes place in the operating theatre, when you are asleep. A blue dye is now injected around the melanoma or scar where your melanoma was and the combination of the radioactivity and the blue staining allows your surgeon to identify the ‘grape(s)’ in the bunch of lymph nodes. This node(s) is removed at the same time as you have the wide local excision of tissue around your melanoma. The blue dye has been used for over 20 years and is accepted practice worldwide. A few patients may have a bad reaction to the blue dye (anaphylaxis) – similar to the reaction some people have to bee stings or nut allergies, and they would need to stay in hospital at least overnight. Generally, this procedure is completed in one day.

The Sentinel Node Biopsy, if positive, removes the node(s) which will contain small numbers of cells. This prevents these cells from growing and spreading to other lymph nodes in the area. If you have a positive lymph node, you will be considered for adjuvant therapy which may improve their survival. This is the main reason why patients choose to have this procedure in addition to a wide local excision.

What happens if I do not have a sentinel node biopsy?

A positive node is found in about 20% (1 in 5) who are offered the procedure. If you are one of the 20% who have a melanoma deposit in your lymph node, but do not have a sentinel node biopsy, then at some time during your follow up, either you or your doctor will feel a lump, where the lymph nodes are. The few cells that would have been found had you had a sentinel node biopsy, will have grown such that they form a lump which you can feel. For the 80% of people who do not have any melanoma in their lymph node(s) and would have had a negative sentinel node biopsy, then the majority will not detect this lump. It is important to know that even if your sentinel node is negative, in a small number or patients (~ 3-4%) the melanoma will come back in a different lymph node. That is why even if you have a negative sentinel node, you are likely to be followed up for 5 years.

Risks and Side Effects

Most people are able to go home on the same day of their surgery, but general anaesthesia an affect your co-ordination and concentration, so you’ll need to avoid driving or drinking alcohol for 24-48 hours afterwards. Simple pain relief is usually all that is needed (paracetamol). Most people will need around a week off work, although this will vary depending on the area your melanoma was removed from and the type of reconstruction required to repair the wound. You are likely to need to either see your local practice nurse or return to the dressing clinic in the hospital where you had your surgery for the first dressing change. Any further dressing changes will be discussed with you then.

The wounds will take several weeks to settle and at least 9 months or so for the scars to soften and settle. The final cosmetic outcome will depend upon what type of reconstruction has been needed for your surgery, how you heal, whether there were any problems during the healing phase, other medical conditions you have and if you are a smoker. Generally, most people are not troubled by their scars.

Side effects might include pain, bruising and swelling in the area where you’ve had the procedure.  The blue dye will make your urine look blue or green for the next couple of days. This is harmless. There is also a risk of an allergic reaction to the dye, an infection in the wound but these risks are low. There will be a collection of fluid in the lymph node area (seoma) but this generally settles, there could be a longer-term collection of fluid in your arms or legs (lymphoedema), but this is rare when only one or two lymph nodes are removed. As with any operation, there is also risk of nerve injury and adverse reaction to anaesthesia. Your surgeon will be able to discuss the risks of the procedure in your particular situation.

More information on sentinel lymph node biopsy can be found here.

Values you may wish to consider during treatment

    • Are there any factors apart from curing your melanoma that you would like to take into account when receiving treatment?
    • Do you want the treatment that is most likely to leave your daily life unaffected?
    • How much do you want to avoid having a visible scar after treatment?
    • How important is it to you to maintain living an active lifestyle, taking into account your daily activities and hobbies?
    • Are there any aspects of the appearance of the scar or the function of that area that are very important to you or that will have a particular impact on you?
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