PETER CHIN
SKIN CANCER AND MELANOMA
SKIN CANCER:
There are various types of skin cancer, with the commonest type being basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and Melanoma. These are often (but not exclusively) related to sun-exposure. (Note: scroll further to see Melanoma below).
SCC and BCC can occur throughout the body and are more commonly found in sun-exposed areas. Incidence of spread to other parts of the body is uncommon. BCC in particular tends to gradually enlarge and if left untreated, may become locally destructive.
SKIN CANCER TREATMENT:
Excision of SCC and BCC is often achievable with a straightforward excision and primary closure. With larger lesions, especially in areas where skin movement is limited, a local flap procedure or skin graft may be necessary. This is often performed by the surgeon under local anaesthetic with the option of sedation if required. Using the appropriate surgical option will ensure removal of the skin cancer with adequate margins and optimal aesthetic outcome.
After surgery, a waterproof dressing is applied and you will be advised to avoid excessive pressure or friction over the area. The dressing is usually removed after 7 days and your surgeon will advise you on the appropriate timing for suture removal, which ranges from 7 to 14 days or longer depending on the tightness of the wound closure. A skin graft, when applied, is usually dressed with several layers of dressing and bandaging to avoid any movement or friction over the skin graft itself. Alternatively, a vacuum dressing may be applied over the skin graft. Your surgeon will usually remove these dressings on day 5 so that the skin graft can be inspected. Appropriate dressings are then reapplied.
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MELANOMA:
Melanoma is a skin cancer that is often but not always related to sun exposure. Melanoma typically occurs in sun-exposed skin but can rarely occur in other areas e.g. eyes, sole of foot and perianal region.
Melanoma arises at the top layer of skin ( often called “superficial spreading”) and over time, invades the deeper layers (“vertical growth phase”). The thickness of the melanoma within the skin layers has correlation with the chances of recurrence. In other words, the thicker the melanoma, the higher the risk of recurrence and potential for spread.
The best possible outcome is achieved when melanoma is removed early or even at a precancerous stage. The term “Breslow’s thickness” is used to describe this thickness which is measured in millimetres under microscopic examination.
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MELANOMA EXCISION:
Treatment requires wide excision of the melanoma with appropriate margins. An initial excision biopsy is usually performed on a suspicious mole and if melanoma is confirmed, the Breslow’s thickness is determined and definitive excision planned. The margin of clearance (distance of the melanoma from the excision margin) is guided by the Breslow’s thickness and the required margin of clearance is usually between 1 to 2 cm.
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SENTINEL LYMPH NODE BIOPSY:
For melanoma with a Breslow’s thickness of more than 1 mm, there should be a consideration for performing a Sentinel Lymph Node Biopsy at the same time as the definitive procedure. The Sentinel node is the first lymph node which receives drainage from lymphatics within a specific region. By removing the sentinel node, one can determine whether melanoma cells have spread to the node itself. This will help with predicting long term outcome and will guide the need for further surgery.
This technique involves injecting a small volume of radioisotope solution prior to surgery and performing a lymphoscintiscan to determine the position of the sentinel nodes. A gamma probe is used during surgery to localise and remove the radioactive sentinel nodes. It is important that the sentinel node biopsy procedure is performed by a surgeon who is specifically trained in the technique and regularly performs the procedure. This will ensure that the correct lymph node is removed so that an accurate result can be obtained.
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METASTASIS:
If a sentinel node or any lymph node, is involved with melanoma, further investigation and treatment will be necessary. This includes staging investigation with CT and/or PET scan. In cases of nodal metastasis, definitive surgery necessitates the removal of lymph node groups within a specific region. This is known as Nodal Clearance or Nodal Dissection. The terminology for this procedure will vary depending on the site of the nodal involvement e.g. Axillary Dissection (for nodes in the axilla/armpit), Neck Dissection and Groin Dissection. Once completed, referral to an Oncologist may be required for consideration of other treatment modalities e.g. Radiotherapy, drug therapy. There has been significant progress in recent times with regards to drug treatment (e.g. BRAF Inhibitor) for melanoma with promising results achieved in cases of metastatic disease. This will likely become a standard treatment option for patients with melanoma in the near future.
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